1 of 8 Full Screen Full Screen Autoplay Autoplay Close Skip Ad × Caption Buy This Photo The top of a modular ATCO style unit being transported on a trailer was sheared off after it struck the South Eagle River overpass in Eagle River, Alaska on Wednesday, March 21, 2018. (Bob Hallinen / ADN) Wait 1 second to continue.

The southbound Glenn Highway lanes at the South Eagle River exit will be closed indefinitely after an 18-wheeler carrying a modular building hit the overpass on Wednesday, according to police.

"Due to (significant) damage to the bridge, the inbound lanes of the Glenn Highway will remain closed indefinitely," the Anchorage Police Department said in a written statement.

The closure could last three to five days while state crews repair the bridge, police said.

"For the Thursday morning commute into Anchorage, traffic will be diverted off of the Glenn Highway at the North Eagle River exit. Drivers will follow detour signs through downtown Eagle River and back onto the Glenn Highway from Hiland Road," police said.

"If you are planning on traveling in the area during this time, including students heading to school via bus or other means, please plan accordingly and drive safely," police said.

All southbound lanes were closed by the accident, police said in an alert shortly after 1 p.m. Wednesday. Drivers heading south on the Glenn to Anchorage were being diverted to the north or south Birchwood exits and routed back on the highway at Hiland Road.

A little after 4 p.m., debris had been removed from the highway, the Alaska Department of Transportation and Public Facilities posted on Facebook.

"We will now begin removing the broken and damaged concrete pieces from the bridge. These must be removed before reopening the highway to traffic," the post said. "This process … will take some time and we don't have a good estimate of when southbound lanes will reopen."

#GlennHighway Southbound at Eagle River: Maintenance has removed the debris from the highway. We will now begin removing... Posted by Alaska Department of Transportation & Public Facilities on Wednesday, March 21, 2018

The accident involved a truck pulling a flatbed trailer with a modular unit on top of it. The truck, the trailer and part of the building crossed under the overpass, but the roof and part of the back of the unit were ripped off and landed on the roadway.

The unit, described as an ATCO-style trailer used on job sites, is owned by William Scotsman Inc. in Anchorage. A company representative reached by phone at the scene said William Scotsman was not responsible for the transportation of the building.

The name on the truck's door identified the trucking company as Bighorn Enterprises.

"We are thankful there were no injuries," the Fairbanks-based company wrote in a Facebook message.

The load didn't require a pilot car, but it was required to have an amber beacon and oversize signage. It was also required to travel at a reduced speed and to travel only during non-peak hours, McCarthy wrote.

Whether the load met those requirements will be part of the state agency's investigation, McCarthy wrote.

The investigation will also help determine who is liable for the repairs, according to McCarthy.

When an overweight or oversize permit is requested, the agency shares information about which bridges will or won't fit the height requirements of their load, so the person applying for the permit can plan their route, McCarthy wrote.

It's unclear how much damage the collision inflicted on the overpass. A bridge inspector arrived at the accident scene by 3 p.m.

The concrete girder bridge is 132 feet long, with a clearance of 18.83 feet, McCarthy wrote.

Alaska bridges get hit "from time to time," McCarthy wrote. The Eklutna overpass was outfitted with extra lights and warnings after it was struck multiple times.

"However, this is a significant hit," McCarthy wrote. "Bridge repairs tend to be very expensive." A recent, similar repair cost about $1 million, she wrote.

Photos circulating on a Glenn Highway traffic Facebook page showed chunks of surface concrete sheared off the bottom of the structure. Exposed rebar was also visible.