"We received a call regarding a vehicle collision that occurred here at Illinois and 24th," said SFPD Public Information Officer Robert Rueca.
Officers responded at 10:25 a.m. Wednesday morning and found five people lying on the sidewalk injured - one critically.
Witnesses say the driver of a white GMC van intentionally ran over the victims and then fled.
VIDEO: 1 killed in San Francisco hit-and-run crash
The witness, who did not want to be identified, said the chain of events started with the driver acting erratically at him.
"He actually banged on his window and yelled some nonsense at me and then threw something at me."
He says the driver got out of his van to pick up the object he threw.
Another witness says five people standing nearby and the driver got into a verbal altercation.
"The guy in the van was just crazy and took it to another level and got out and went after the guys with an ax and they just took off their belts and were lashing at him."
Both witnesses say the group overpowered the driver, taking the ax away from him.
"He got into the van screaming at them, yelling at each other and the guys started to walk away and he flipped the van around and drove it on the sidewalk, full pedal to the metal and drove over four of the five."
Early this afternoon, police stopped a white van with numerous suspicious dents on the front and side.
They arrested the driver, who a reliable police source said was identified as 33 year old Mark Dennis of San Francisco.
SFPD has arrested Mark Dennis in the hit and run in the Bayview which sent five people to the hospital. His white GMC Safari also recovered at arrest scene has numerous suspicious dents.— Vic Lee (@vicleeabc7) March 28, 2018
POlice have stopped a vehicle couple miles from hit and run scene and detained someone inside.. It may be the driver, source says. pic.twitter.com/lmc0K0qFr5— Vic Lee (@vicleeabc7) March 28, 2018
Witness says driver intentionally ran over the group after altercation. Witness says driver first wielded an ax swinging at the group then ran into van and rammed it into them and speeding off. Sfpd not confirming witness account. pic.twitter.com/OjxQwG7U7y— Vic Lee (@vicleeabc7) March 28, 2018
Driver of vehicle runs over five people in Bayview district of SF. Police looking for driver now. At least one in critical condition at SFGH. Others taken also to hospital. pic.twitter.com/hf75piSHWZ— Vic Lee (@vicleeabc7) March 28, 2018
#SFPD investigating hit and run incident at 24th & Illinois Streets. Please avoid the area until further notice.— San Francisco Police (@SFPD) March 28, 2018