DIAMOND BAR, Calif.—Los Angeles County authorities are searching for three people, including one who posed as a police officer, in a home-invasion robbery in Diamond Bar.

Sheriff's Sgt. Christina Baker tells City News Service a mother, grandmother and three children were herded into a room Sunday night and one of the women was tied up.

KABC-TV says one of the intruders was dressed in a tactical vest and gave the impression of law enforcement. He apparently implied that the men needed to investigate some kind of illegal activity in the house.

It wasn't immediately clear what was stolen.

Investigators are looking for three men.

None of the victims were injured.