The response by law enforcement to protesters in Ferguson, Mo., is being criticized for its level of force and use of military-style equipment. We've labeled the weapons and gear being used by police in these photos from Ferguson. (Tom LeGro and Thomas Gibbons-Neff/The Washington Post)

In one photo, two officers wearing camouflage and thick vests sit atop a vehicle, a gun pointed at a crowd. In another, a group dressed like soldiers advances on a man, guns drawn and faces obscured by gas masks.

In their response to the protests and civil unrest after the fatal shooting of 18-year-old Michael Brown by a Ferguson, Mo., police officer last Saturday, local authorities have employed armored vehicles, noise-based crowd-control devices, shotguns, M4 rifles like those used by forces in Iraq and Afghanistan, rubber-coated metal pellets and tear gas.

The anger of residents at first revolved largely around a desire for information about the shooting, but that rage is now rivaled by anger over the authorities’ show of force since the weekend.

“What struck me as I watched on TV was that I was looking at sniper rifles being pointed during the day at peaceful protesters,” said David Goldstick, 38, a former Marine who said that images from clashes Wednesday night impelled him to come out and join the demonstration. “The violence seems to be incited almost exclusively by the police — and it’s not even police, it’s a paramilitary force.”

Ferguson Police Chief Thomas Jackson challenged that characterization Thursday afternoon during a news conference.

Meghan Flannery, a protester in Ferguson, Mo., was arrested Wednesday night. She describes the impact of the militarized police presence in Ferguson and what it was like to be arrested. (The Washington Post)

“It’s not military, it’s tactical operations,” he said. “It’s SWAT teams.”

He said he was satisfied that no one had been seriously injured in a city that he described as a “powder keg.” However, one officer was hit with a brick and broke an ankle, and a second also was hurt.

Gov. Jay Nixon (D) promised Thursday to change the tone of the response, announcing that the Missouri Highway Patrol would take over security.

But the show of force highlights what civil liberties advocates describe as a decades-long militarization of America’s police forces and elicits strong responses from some local and federal officials and veterans of recent wars.

Attorney General Eric H. Holder Jr. said he was “deeply concerned that the deployment of military equipment and vehicles sends a conflicting message.”

Sen. Claire McCaskill (D) of Missouri called on authorities to “demilitarize this situation,” adding in a statement that “this kind of response by the police has become the problem instead of the solution.”

Sen. Rand Paul (R-Ky.) complained in a Time magazine essay that “Washington has incentivized the militarization of local police precincts by using federal dollars to help municipal governments build what are essentially small armies.”

One program often credited as a source of military resources deployed by police department is the Defense Department’s Excess Property Program — also known as the 1033 program — which gives equipment, including weapons, to law enforcement agencies.

Transfers through the program have increased dramatically in recent years.

In 2006, it made 34,708 transfers worth $33 million to law enforcement agencies. Last year, the number grew to 51,779 transfers valued at $420 million, according to data provided by the Defense Logistics Agency, which manages the program. Through April of this year, the agency had made 15,516 transfers of equipment worth $206 million.

“Of all the equipment provided to law enforcement agencies through the LESO [1033] program, only 5 percent are weapons,” DLA spokeswoman Michelle ­McCaskill said. Since the program started nearly two decades ago, it has transferred equipment valued at $5.1 billion.

The Ferguson Police Department has received a small amount through the program in recent years, including non-tactical items such as field packs, first-aid kits, wool blankets and medical supplies.

The Defense Department would not provide a breakdown of tactical items given to the Ferguson police exclusively but said that law enforcement agencies within St. Louis County — which includes Ferguson — have in recent years received a dozen 5.56mm rifles, half a dozen .45-caliber pistols, night-vision goggles and a bomb-disposing robot.

But 1033 is just one of a set of federal programs that have facilitated the militarization of local law enforcement agencies, said Kara Dansky, senior counsel at the American Civil Liberties Union’s Center for Justice and the lead author of a June report on the issue. Police departments also have access to billions of dollars in funding from the Justice and Homeland Security departments.

“The militarization of policing is actually not a new problem,” Dansky said.

The police response in Ferguson was so strong that officials in nearby St. Louis wanted nothing to do with it.

Ward 18 Alderman Terry Kennedy e-mailed St. Louis Police Chief Sam Dotson on Wednesday night to ask him to stop providing assistance in Ferguson. Only four traffic officers had been involved, Dotson replied, promising none would offer assistance Thursday.

“My gut told me what I was seeing were not tactics that I would use in the city, and I would never put officers in situations that I would not do myself,” Dotson later told the St. Louis Post-Dispatch.

For some war veterans, the response has appeared to be not only heavy-handed but out of step with the most effective ways for both law enforcement and military personnel to respond to demonstrations.

“You see the police are standing in line with bulletproof vests and rifles pointed at people’s chests,” said Jason Fritz, a former Army officer and an international policing operations analyst. “That’s not controlling the crowd, that’s intimidating them.”

Scriven King, a 10-year veteran of the Air Force’s law enforcement component and a SWAT officer, attributed the initial spasm of violence to a lack of leadership and mismanagement of public perception by the Ferguson Police Department. “The first thing that went wrong was when the police showed up with K-9 units,” King said. “The dogs played on racist imagery. . . . It played the situation up, and [the department] wasn’t cognizant of the imagery.”

King added that, instead of de-escalating the situation on the second day, the police responded with armored vehicles and SWAT officers clad in bulletproof vests and military-grade rifles.

Local law enforcement has for decades become increasingly militarized, Dansky said.

“It has been going on, particularly in poor communities and communities of color, for decades,” she said. “The problem is that it has been underreported and under-documented in those communities.”

The trend swelled after the Sept. 11 attacks, as a new stream of Homeland Security assistance to local law enforcement opened to combat terrorism, according to the ACLU report.

In it, Dansky and her colleagues reviewed data on more than 800 SWAT team deployments conducted by 20 law enforcement agencies from 2011 to 2012.

In 79 percent of the incidents, a team was deployed to search a home, and more than three in five SWAT deployments involved searches for drugs.

“The use of a SWAT team to execute a search warrant essentially amounts to the use of paramilitary tactics to conduct domestic criminal investigations in searches of people’s homes,” the report’s authors wrote.

Wesley Lowery, Kimberly Kindy, Christopher Ingraham and Thomas Gibbons-Neff contributed to this report.