PORTLAND -- Police think the wrong-way driver who crashed head-on into a semi-truck early Thursday morning may have been drunk, according to investigators.

The collision occurred just before 3 a.m. at the Interstate-84 westbound and Interstate-5 southbound on-ramp and backed up freeway traffic for nearly four hours.

Ken Burt, 43, was driving northbound in the southbound lanes of I-5, police said, though traffic officers said they had not yet determined where Burt entered the freeway the wrong way or how long he had been traveling before he hit the truck.

Burt had to be cut out of his Jeep Cherokee and taken to Legacy Emanuel hospital with injuries that were not life-threatening, police said.

As of 7:15 Thursday morning, police had not released the name of the driver of the semi-truck. But they said he was not injured.

The on-ramp was blocked to all inbound traffic from I-84 onto I-5 Southbound until 6:30 a.m.

The impact of the crash also ruptured the semi-truck's fuel tank, causing a diesel spill. Crews worked for hours cleaning up the mess.