HUNTSVILLE, AL -- Two men impersonating police officers burst into a northwest Madison County home Sunday night, robbing the couple inside and injuring the man, authorities said.

The two men, dressed like police officers, knocked on the door of a mobile home near Alabama 53 and Ready Section Road in the Toney community around 10 p.m., said Madison County Sheriff's Investigator Chad Brooks. When the occupants opened the door, the robbers pushed their way inside, hit the man in the head with the gun, tied the man and woman up and robbed them, Brooks said.

The two robbers got away with about $200 in cash, Brooks said.

All Madison County Sheriff's deputies are required to carry a department-issued identification card with them any time they are working, even if out of uniform, Brooks said.

"It's always best to verify who you're talking to before opening doors," he said.

The two robbers did not identify themselves as officers, Brooks said, but they were wearing the clothes.

"Police impersonation is extremely rare," he said. "It's a felony offense beyond anything else, and it's a very serious offense."

Brooks said the sheriff's department takes impersonation seriously because of the harm it can cause. It breaks down the barrier of trust in the community and puts plain-clothes officers at risk, he said.

"This is the only case we have where someone represented themselves to be a police officer," Brooks said. "It's a concern, and we are actively working it."