A man holding what was believed to be a rifle caused panic on a Bronx bus, injuring a 77-year-old woman, police said Sunday.

The gunman boarded the back of a Bx15 bus just before 10 p.m. Saturday on 3rd Avenue and Tremont Avenue, cops said. The suspect was holding a bag and what witnesses believed to be a large gun.

“I’m gonna clear the world, hide your kids,” the suspect said, according to cops.

The passengers rapidly fled the front of the bus, managing to injure the elderly passenger, who was boarding, police said.

Both the elderly woman and a pregnant woman who suffered a panic attack were transported to Saint Barnabas Hospital and were in stable condition.

There were no immediate arrests.