COLORADO SPRINGS, Colo. -

Perhaps the most noticeable aspect of the police response to rioting in Ferguson, Missouri, is the use of military-grade equipment.

Authorities are using bulletproof vests and helmets, tear gas, automatic weapons and even armored vehicles to quell rioting and discourage looting.

This equipment is increasingly being obtained, often at little or no cost, by local police departments and sheriff's offices from the U.S. Department of Defense.

The American Civil Liberties Union has expressed concern about the trend in its report, "The Excessive Militarization of American Policing."

"Streets in our towns and cities are becoming war zones," said ACLU spokeswomen Kara Dansky. 

"(Take) an MRAP for example.  It's a mine-resistant, ambush-protected vehicle.  It's built to withstand armor-piercing bombs.  This is not something that we need in American communities," she said.

Dansky said using military-level equipment and tactics in normal law enforcement situations is unnecessary.

"(Local) law enforcement will drive up in an armored personnel carrier, raid a person's home, holding assault rifles, holding people at gunpoint, yelling at everyone to get on the floor," she said.  "This is an extremely traumatic experience and we've seen over and over again situations like this where people are traumatized and sometimes people are injured and killed."

Two Colorado Springs men agree with Dansky. 

Lance Dawson said officers' attitudes change when they wear and use military-grade equipment.

"It's a mind change when you get armored up like that," he said.  "I used to be in the military.  We could be as mellow as anything but the minute we strapped on that body armor, our personalities changed, our attitudes changed.  Let the police just be the police.  That's what we have SWAT teams for."

Ricky Nibblins said an extension of the military mindset is that unarmed Michael Brown, 18, died after being shot several times during an apparent struggle with a police officer.

"Armored vehicles and tear gas, that's taking it to the extreme," he said.  "Is there a line that needs to be drawn?  I think it depends on the situation."

However, law enforcement agencies say they're only meeting their responsibility to maintain law and order.  Several business owners in Ferguson have criticized officers for not doing enough to prevent looting and property damage.

Military equipment and tactics, agencies said, also help them stay on equal terms with criminals who have equal or greater firepower.

The ACLU is also concerned about local law enforcement overreacting and using military equipment when not warranted, as well as agencies having enough money to regularly and adequately train officers in the use of military equipment and tactics.

Last year alone, the Defense Department gave local law enforcement $450 million in equipment.  Colorado received equipment valued at $22 million.

In January, Colorado Springs police received seven Humvees.   Police said the military-style, all-terrain vehicles would be used for emergencies such as travel during floods and blizzards, but said they also will be useful in shooting, hostage and standoff situations.