Inside the truck were at least two people, including Erkinson K. Bossy, 23, who is suspected of driving the getaway car in a Jan. 22 robbery and shooting at a Kelso convenience store that left the store clerk, Kayla Chapman, 30, dead.
Police believed ahead of the chase into Portland that Bossy was armed, Kapp said.
The pickup traveled onto southbound Interstate 205 and crossed the Glenn L. Jackson Memorial Bridge into Portland, according to emergency radio traffic monitored at The Columbian. At some point on I-205, shots were exchanged between the pickup and Porter. Investigators have not said who fired first.
The shootout spanned a total of 6 miles on I-205 and I-84, according to Portland police.
Police performed a Pursuit Intervention Technique, or PIT, maneuver, on I-84 to stop the pickup and took Bossy and an unnamed person into custody.