A Baltimore city police officer delivered the fright of a lifetime to a haunted house employee, pulling a gun on the chainsaw-wielding man at the end of his act, authorities said on Monday.

Sergeant Eric Janik, 37, was charged with assault and reckless endangerment for pointing his service handgun at the worker, who was dressed as Leatherface, the killer from , Baltimore County police said.

The employee, Mike Morrison, followed Janik and several other people up a staircase Sunday night at the end of the haunted house tour in a bid to get "one last scream" out of them, police said.

When the group exited into a parking lot, Janik pulled his gun and pointed it at Morrison from less than three metres away, according to police and Morrison, who said he dropped the chainsaw, put his hands up and backed away. The saw had no chain.

Only then did Janik identify himself as a police officer, said Morrison, who retreated into the building.