Two men sustained injuries in a head-on collision on the H-1 freeway in the McCully area early today.

Police said a vehicle operated by a 43-year-old Wahiawa man was traveling in the wrong direction in the eastbound lanes of the freeway just before 12:30 a.m. when it collided with a vehicle operated by a 23-year-old Honolulu man just after the McCully Street overpass.

Both men were taken in critical condition to a hospital. Their condition later improved to serious condition.

Officers temporarily closed all eastbound lanes of the freeway and rerouted traffic at the Punahou off-ramp as police investigated. Officers reopened lanes sometime before 4:15 a.m.

Police said speed or alcohol were not factors in the crash.

An investigation is ongoing.