Tucson police arrested 22-year-old Joseph Zarate, who is suspected of punching a Sun Tran bus driver in the face on Feb. 4.

Zarate is facing assault, disorderly conduct and threats and intimidation.

On Feb. 4 at 3:20 p.m., officers responded to North Oracle and West Roger roads to a report of an assault on a bus driver by a man boarding a bus, said Officer Daniel Lucas, a department spokesman, last week.

Officers learned that the bus driver and passenger argued before the passenger lifted up his shirt and showed what is believed to be a BB gun tucked into his waistband, police said.

The man then punched the driver in the face and left the bus with a pregnant woman, Lucas said.

Zarate was questioned by police Feb. 9 when he was found at a bus stop near South Park Avenue and East Fair Street, according to a Tucson Police Department Facebook post.