It's been a stabby week in San Francisco, and it's only Wednesday. In addition to a knife attack over the weekend and a slashing on Tuesday, three more men fell prey to bladed violence this morning: two in a North Beach altercation, and a third while riding a Muni bus.

In the first such incident, two men were arguing at around 2:55 a.m. on the 500 block of Francisco Street, which is between Mason and Taylor Streets. As the conflict intensified, one of the men stabbed the other in the head, San Francisco Police Department spokesperson Sergeant Monica MacDonald says.

A good samaritan tried to break the fight up, but the knife-wielding man stabbed him in the back, MacDonald says.

Both men suffered injuries that do not appear to be life-threatening, MacDonald says. The suspect fled and remains at large. MacDonald did not have any additional suspect information, including a description, at publication time.

Less than a hour later, police were called to the West Portal Muni station, after a man was stabbed while riding a Muni bus, MacDonald says.

Details on this incident are still sort of sketchy, but here's what MacDonald knew as of this morning: at 3:50 a.m., two men were riding the bus when the suspect, described by ABC7 as " Filipino man in his 40s," "said something to the victim and then fled off of the bus."

Another Muni passenger then noted that the victim was bleeding, and the victim realized that he'd been stabbed. He was transported to San Francisco General Hospital for treatment of his injury.

Know anything about either case, or about the stabbings from Saturday or Tuesday (those suspects remain at large, too)? Then call San Francisco police at (415) 575-4444 or can send a tip by text message to TIP411 with “SFPD” in the message.

Related: Man Stabbed In Mob Attack In Mission, Another Slashed In Face At Fifth And Market