The incident happened at around 3 a.m. at the east end of the Dunsmuir Viaduct, a raised, one-way stretch of road carrying traffic from east Vancouver into the downtown core.
One car has flipped on its roof, spreading debris across the two-lane viaduct and closing the busy commuter link for several hours.
Vancouver Police have not confirmed witness reports that street racing may have played a part in the crash, but a police spokesman is heading to the scene.
Residents living along Prior Street, which leads to the viaduct, have been urging the city to impose measures to slow down traffic in the neighbourhood.
They also fear the city's plans to demolish the Dunsmuir and Georgia viaducts will channel even more traffic onto Prior Street, and they say the latest proposals due to be considered by council fail to address their traffic concerns. (CKNW, News1130)