Alaska State Troopers say a carjacking suspect crashed multiple cars Tuesday afternoon, leading authorities to shut down the highway south of Portage. 

Megan Peters, spokesperson for AST, says the Seward Highway was shut down in both directions between mileposts 63 and 68 for about an hour. The stretch of highway runs south of Portage before the Hope turn-off. 

Around 12:45, AST received multiple reports of a Toyota pickup truck being driven erratically, southbound near Portage. Troopers say the suspect crashed the pickup at mile 72, got out of his car and flagged down a passing motorist.

The suspect threatened the Good Samaritan driver with either a pipe or a club, troopers say, and carjacked the victim's black pickup and continued southbound. The suspect crashed the stolen pickup near the Bertha Creek campground near milepost 65 and took off on foot. 

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A Forest Service official and a good Samaritan apprehended the suspect around 1:20. The highway was reopened by 3. 

Witnesses told KTVA's crew on scene that the suspect was impaired on something. 

Troopers, who haven't yet identified the man, say he did not have any outstanding warrants. 

Peters says K-9 units and a helicopter assisted; the Forest Service and Anchorage Police also responded. 

Troopers say intermittent closures are likely while detectives continue their investigation.

Emily Carlson contributed to this report.

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