Police spokesman Officer Albie Esparza said a 19-year-old San Francisco man and an 18-year-old Los Angeles man got into an argument with two male suspects near the intersection of Irving Street and 21st Avenue at about 1 a.m.
Several other men arrived and a fight broke out that involved as many as 10 suspects, Esparza said. Two of the suspects attacked the victims with the knife and tire iron.
The 19-year-old man was treated at a hospital for head injuries and was expected to survive, Esparza said.
The suspects were seen leaving the fight in two vehicles, a green Ford minivan and a black two-door Honda, police said.
Officers stopped the minivan several blocks away and detained two men inside, but they were not arrested, according to Esparza.
"They're involvement (in the fight) is unknown," Esparza said.
An investigation is continuing.