The San Francisco Police Department is seeking a knife-wielding party bus rider today, after he reportedly stabbed another partier/rider in the chest.

The Ex reports that at 2:52 a.m. Sunday, a fight broke out on a party bus on the 900 block of Connecticut Street, which runs through the Potrero Terrace public housing projects.

A 43-year-old man stepped in to break up the fight, but was stabbed in the chest by a male suspect, KRON4 reports.

The aspiring peacekeeper is expected to recover from his wounds. His alleged attacker "is an unknown man," the Ex reports.

The suspect remains on the loose as of Tuesday morning, but police ask that if anyone witnessed or has information on this stabbing, they contact SFPD's anonymous tip line at (415) 575-4444 or text-a-tip to TIP411 with "SFPD" at the beginning of the message.

Related: Everyone Hates Party Buses