The pursuit began after police responded to a call of a gunman in an orange safety vest who threatened a man in downtown L.A. at about 8:15 a.m.
Police followed the suspect's van onto the 110 Freeway in South L.A., and then onto the eastbound 91 Freeway.
The chase ended about a half hour later in Carson. Three men were taken into custody without incident.
Authorities believed guns or ammunition may have been tossed on the freeway, so the California Highway Patrol closed about a mile and a half of the southbound 110 lanes from Gage to Vernon.
The freeway was reopened just before 11 a.m., but it wasn't soon enough for the hundreds of drivers stuck in traffic.
"You can't move, just like sitting in the car with hot heat and sweating," said frustrated driver Michael Valverde.
It is unknown if any evidence was found on the freeway.