Authorities charged an Oxon Hill man yesterday with being a member of a gang of heavily armed bank robbers and arrested two other suspects in a series of raids that netted assault weapons, body armor and cash, law enforcement officials said.

They said two additional suspects were already in jail.

Aaron B. Perkins, 27, was charged with conspiracy to commit bank robbery and being an accessory after the fact, the FBI said. The arrests and raids were the first in a case that officials had feared would end in bloodshed for responding officers or bystanders.

Details were still fluid yesterday as police and federal agents questioned suspects and witnesses and tried to track down four or five others believed to have ties to the gang. Police said the band of robbers stole more than $350,000 in four holdups in the District and two in Prince George's County since January, brandishing assault rifles and threatening tellers and customers.

"We feel good that we're in a position now to better understand who may be responsible for this series of robberies," said D.C. Police Chief Charles H. Ramsey. "We have a significant cache of weapons and some money and some people we're talking to, to see what they know. . . . We are very comfortable where we are right now, but we're continuing to investigate."

Police said they arrested the two other suspects during the early-morning raids in Silver Spring, Oxon Hill and Northwest Washington. But numerous other people are under scrutiny. Investigators said that two other men, in custody in connection with other crimes, could be part of the robbery gang. For weeks, authorities have said that the gang could have numerous members -- not only the masked men captured on videotape going into the banks but also unseen lookouts.

The raids were carried out by D.C. police, the U.S. Marshals Service, the Bureau of Alcohol, Tobacco, Firearms and Explosives, the FBI and officers from Montgomery and Prince George's counties. Many officers wore body armor and carried high-powered weapons in case they encountered resistance. No one was hurt.

Authorities said they arrested Miguel Morrow, 26, at a girlfriend's apartment in the 14000 block of Grand Pre Road in Silver Spring. Neighbors described a loud noise that woke them at 6 a.m., followed by police shouting as they stormed the third-floor apartment.

"I heard a loud boom, sounded like a bomb, and I heard someone say, 'Get down on the ground,' " said Dominica Mills, 26, a resident. "They carried a guy out."

Morrow had been sought in two unrelated shootings this spring in Northwest Washington. He has been on probation since May after pleading guilty earlier this year in Montgomery County Circuit Court to a charge of possession with intent to distribute marijuana, records show.

The other bank robbery suspect arrested yesterday was identified by law enforcement officials as Guidel Olivares, 45. He was arrested on a weapons charge during a raid at a rowhouse in the 3100 block of Sherman Avenue NW.

In that house, police found more than a dozen guns, including a half-dozen assault rifles, body armor, silencers and cash stained with red ink that police said came from a dye pack that exploded in the gang's most recent heist June 29 on Connecticut Avenue NW.

Investigators had been told that the gang had stashed weapons and some cash in the house, police said.

Perkins was arrested in the overnight hours after visiting Morrow in Silver Spring, the U.S. Marshals Service said. Police said they stopped his car and seized a semiautomatic handgun. He was charged with illegally possessing a firearm, authorities said.

A subsequent search at Perkins's apartment in the 2600 block of Brinkley Road in Oxon Hill turned up two assault rifles, a handgun and body armor, police said. They declined to provide details about the evidence that led them to charge Perkins with bank robbery yesterday.

Like Morrow, Perkins had earlier brushes with police this year. He was arrested Jan. 23 -- one day after the first bank robbery -- in Oxon Hill and charged with stealing a car and a weapons offense. He pleaded guilty to those charges June 9 and was to be sentenced Aug. 30. One of the bank robberies took place three days after Perkins entered the guilty plea.

Police said they began making significant progress in the investigation after delving into the criminal records of people who had been charged with possessing assault weapons or using them in crimes.

Morrow's name, for example, turned up in two shootings. He was charged with assault with intent to kill in an April 23 shooting on Longfellow Street NW in which a 45-year-old woman was hit by a stray bullet while trying to protect a child.

He also was charged in a May 15 shooting on Ninth Street NW in which the victim was hit in the leg. A second suspect in that incident, Lionel Stoddard, 23, has been in jail since his arrest June 28. Police said that Stoddard, of Northwest Washington, is viewed as a bank robbery suspect even though the last holdup took place a day after his arrest.

On Sunday, police and federal agents were staking out Morrow when he got into a stolen Mercedes-Benz with another man, police said.

Officers chased the Mercedes into Alexandria, where it stopped on Quantrell Avenue, police said. Morrow jumped from the car and ran away, authorities said.

The other man was arrested after he tried to carjack two cars and break into nearby condominiums, police said.

That man was identified as Noureddine Chtaini, 29, of the 4000 block of Van Ness Street NW. Police officials said that Chtaini also is a suspect in the bank robberies and that he provided information after his arrest that gave police a major break in the case this week.

Yesterday's developments came after law enforcement officials issued urgent appeals for the public's help in halting the string of robberies. The FBI had offered a reward of up to $50,000 for information leading to arrests and convictions.

Top police officials had expressed concern that someone would be killed or hurt because of the firepower packed by the gang. The men fired shots in three robberies, including some at a Prince George's County police officer in a May 10 holdup. The robbers typically stole vans to use in the crimes and the getaways, then set them afire in nearby neighborhoods.

During their most recent robbery on June 29, they fired two shots into the ceiling of the SunTrust bank in the 5000 block of Connecticut Avenue NW. Some of the most gripping images of the robberies have come from that holdup. A photographer for WTTG-TV (Channel 5) was nearby on another assignment when the robbers stormed into the bank.

Staff writers Cameron Barr, Nicole Fuller, Paul Schwartzman, Leef Smith, Jamie Stockwell and Clarence Williams and staff researcher Bobbye Pratt contributed to this report.

Montgomery County officers talk outside the apartment building in Silver Spring where police arrested one of the bank robbery suspects.Julio Morales stands on the porch of a rooming house on Sherman Avenue NW that police raided, seizing weapons and cash and making one arrest.