Federal prosecutors announced terrorism charges against the surviving suspect in the Boston Marathon bombing on Monday, outlining a chilling plot in which the man and his brother allegedly used low-grade but deadly explosives timed to detonate a block apart.

As he lay seriously injured in a Boston area hospital, Dzhokhar Tsarnaev, 19, was charged with using a weapon of mass destruction and malicious destruction of property, counts that could bring him the death penalty. He made his first court appearance in an unusual, non-public proceeding in which a federal judge and several lawyers went to his hospital bed.

The toll from the two blasts, according to court documents and interviews on Monday, could have been far higher. Tsarnaev and his brother, Tamerlan, 26, who was killed Friday after a firefight with police, had a homemade arsenal of explosives. Some law enforcement officials said they think the brothers were planning more attacks.

The pair also apparently had no escape plan. The FBI found in Dzhokhar Tsarnaev’s college dorm room what appeared to be the same black jacket and white hat he wore on the day of the attack, court documents said.

As the legal machinery began moving, the rituals of recovery continued in Boston. Near the marathon finish line, where three people were killed and more than 200 injured, residents and office workers poured out of buildings on Monday for a moment of silence at the same time the blasts occurred one week ago.

See the names and stories of the Boston Marathon victims

When the clock reached 2:50 p.m., hundreds of people — standing on sidewalks, street corners and building steps — froze in place. Even some cars stopped moving, ignoring green lights until cabs honked for them to move. Some people wiped away tears; others hugged.

Within five minutes, the buzz of life again hit the streets. Yet earlier in the day, the atmosphere was equally solemn in a quiet Boston suburb as people came together to mourn Krystle Campbell, a 29-year-old restaurant manager, in the first funeral for a victim of the attack. Firefighters, members of the Guardian Angels and motorcyclists joined Campbell’s high school classmates and others, the mourners dressed mostly in black and standing quietly in a cold wind.

The criminal complaint against Dzhokhar Tsarnaev, filed in U.S. District Court in Boston, ended a debate over how one of the first successful terrorist attacks on the U.S. homeland since Sept. 11, 2001, should be handled. Some congressional Republicans had insisted that Tsarnaev be designated an “enemy combatant,’’ which would enable the government to charge him under the laws of war in a military commission or to hold him indefinitely.

White House press secretary Jay Carney rejected that approach on Monday, saying that the suspect cannot be tried in a military commission under federal law because he is a U.S. citizen. “We will prosecute this terrorist through our civilian system of justice,’’ Carney said at a White House news briefing.

Massachusetts public defenders Miriam Conrad, William Fick and Timothy Watkins, who have been appointed to represent Tsarnaev, did not reply to requests for comment Monday.

The three defense lawyers, along with two federal prosecutors, joined Tsarnaev for the court session at his hospital bed, where the suspect is recuperating from gunshot wounds to the head, neck, legs and hands, according to a transcript provided by the court.

Federal Magistrate Judge Marianne Bowler advised Tsarnaev of his rights and the charges against him, the transcript said.

“How are you feeling?” a doctor, identified as Dr. Odom, asked. “Are you able to answer some questions?” Tsarnaev “nods affirmatively,’’ said the transcript, which added that the only word he spoke during the hearing was “no” when asked whether he could afford a lawyer. Fick said he would reserve questions about bail and other matters, according to the transcript. The judge then ended the session, saying she found the defendant “alert, mentally competent and lucid.”

Investigators have been eager to question Tsarnaev but have said he is unable to speak because of the neck injuries. It was unclear Monday whether he has been able to provide any information.

An affidavit by FBI agent Daniel R. Genck that accompanied the complaint portrayed Tsarnaev as a relatively low-tech operative who was caught on the day of the marathon on multiple surveillance cameras. Genck described how Tsarnaev and his brother were captured on camera walking near the finish line April 15, both carrying large knapsacks. They stood together for several minutes, appearing to watch the race.

Tamerlan broke off and walked toward where the first improvised explosive device would soon detonate, Genck said. Three minutes later, Dzhokhar walked in the same direction, then stopped and slipped his knapsack onto the ground. He then stood looking at his cellphone, and even appeared to snap a picture with it.

About 30 seconds before the first explosion, Genck’s affidavit said, Dzhokhar, standing in front of a restaurant, lifted the phone to his ear as though he were speaking and held it there. The first bomb exploded. “Virtually every head turns to the east [toward the finish line] and stares in that direction in apparent bewilderment and alarm,’’ Genck said.

Dzhokhar, referred to in the complaint as “Bomber Two,’’ stood out. “Virtually alone among the individuals in front of the restaurant,’’ the affidavit said, he “appears calm.’’

He then rapidly walked away from the direction of the first explosion, his knapsack on the ground.

About 10 seconds later, the second bomb exploded where his knapsack had been, Genck said.

The document also provides details about the explosives used in the attack, saying they were “low-grade” and housed in pressure cookers that contained metallic BBs and nails. Many of the BBs were encased within an adhesive material, the complaint said, and several explosives discovered in a car the brothers used and at the scene of the shootout with police in Watertown, Mass., were similar.

Authorities were continuing a worldwide investigation of the marathon attack and looking into whether foreign or domestic terrorist groups helped. No evidence of such a connection has emerged, law enforcement officials said.

Authorities are trying to trace a handgun recovered from the suspects. Law enforcement sources said the effort has been delayed because the serial number was removed. Technicians are working to determine the numbers, after which the weapon will be traced by a Bureau of Alcohol, Tobacco, Firearms and Explosives facility in West Virginia.

New information also emerged about Tamerlan’s earlier brushes with the law.

Authorities in Massachusetts confirmed that they are investigating whether the elder brother may have been connected to a triple homicide in Waltham, Mass., in September 2011, prosecutors said. The Boston Globe reported that Tamerlan was friends with Brendan Mess, 25, one of three people found dead in an apartment on the afternoon of Sept. 12.

MaryBeth Long, a spokeswoman for the Middlesex County District Attorney’s Office, told The Washington Post that authorities “will review any new information that may come to light in that case as a result of the investigation” of the marathon bombing.

Court records in Cambridge, Mass., meanwhile, showed that Tamerlan was arrested on charges of assault and battery in July 2009 after slapping a girlfriend. The incident occurred at his apartment on Norfolk Street after an argument between him and Nadine Ascencao over another woman, according to the incident report. The records indicate that the case was dismissed about six months later.

Johnson reported from Boston. Kathy Lally and Will Englund in Moscow and William Branigin, Scott Wilson, Greg Jaffe, Julie Tate and Joel Achenbach in Washington contributed to this report.