UNION CITY -- A police chase that involved officers in three cities and a shotgun discharge ended in the arrest of three suspects -- including two who were nabbed by police dogs on Monday night.

The chain of events began at 10:30 p.m. when a Union City police officer pulled over a white, four-door sedan with four people inside for a traffic violation near the intersection of Ithaca Street and Tamarack Drive, Union City police Cmdr. Ben Horner said.

When the car stopped, police removed the driver of the vehicle -- identified as Caylan Lillard, 20, of Oakland -- to search him. As they did, the passenger slid into the driver's seat and drove away, Horner said.

As the car drove off, an occupant inside threw an object wrapped in a jacket outside of the vehicle. The object, later determined to be an illegal sawed-off shotgun, discharged as the weapon hit the ground, Horner said.

The weapon was recovered on Carrol Avenue in Hayward and police said no one was injured.

"Officers searched door-to-door to make sure no one had been hit by the exploding shotgun round," Horner said.

Meanwhile, a San Leandro police officer observed the car entering their city and a short pursuit took place. At some point the vehicle stopped and its occupants ran off, Horner said.

Officers from Union City, Hayward, San Leandro and the California Highway Patrol then set up a perimeter and with the help of police K-9s two other suspects -- Anthony Pearson, 29, of Oakland and Melissa Villalovos, 30, of Hayward -- were caught and arrested on suspicion of drug and weapon charges, Horner said. Narcotics including methamphetamine and marijuana were recovered during the arrest.

The fourth suspect remained at large on Tuesday.

Anyone with information about the shooting is asked to call police at 510-675-5224.

Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.