The Saskatoon Fire Department had removed 40 per cent of the ammonia contained in a overturned semi-trailer on College Drive as of late Thursday night. 

The department was planning to raise the truck upright, assess its damage and decide whether to remove the rest of the anhydrous ammonia from the tanker or safely tow the rig out of the city, according to an update issued late Thursday. 

A second tanker truck had arrived at the scene Thursday afternoon to help remove the ammonia, with the fire department deeming the area safe. 

Motorists were asked to avoid the area if possible.

Some drivers had gone off-road to avoid traffic lineups at around 5:15 p.m. CST, near an off-ramp onto Circle Drive North.

Saskatoon drivers go off-road to avoid traffic jam after semi-trailer rollover0:22

It happened in the area specified on this map:

where people going offroad

(Thilina Bandara)

The City of Saskatoon says motorists leaving the city centre and travelling eastbound on College Drive can travel north and south via Circle Drive, while drivers travelling westbound into the city on College Drive must exit at Central Avenue.

Change your route: city

The city says residents of Brighton, Willowgrove, Arbor Creek, Erindale and areas east of the city limits are being asked to use Eighth Street to McOrmond Drive or Circle Drive to Highway 16 to Zimmerman Road, by Saskatoon's newest Costco.

Residents of Sutherland, Forest Grove, Silverspring and Evergreen are encouraged to use Attridge Drive and 108th Street.

"Traffic signals are being adjusted at key intersections to assist with the change in driving routes, but everyone is reminded this closure will cause delays," the city said in a release.

"Please allow for additional travel time to reach destinations, and remember to respect all detour signage."

Updates will be issued as roadways reopen.

No injuries have been reported.

The truck's driver told CBC he's not sure what happened, but he felt the rear tank shift as he came off Circle Drive onto College Drive.

The fire department said during an early evening update Thursday that the cause was still under investigation.

Saskatoon truck carrying ammonia tips over on College Drive0:26