The Oklahoman, John Clanton, Associated Press
Officials block a section of I-40 east of downtown Oklahoma City on Wednesday, May 11, 2011 after a tractor trailer rig carrying military explosives was involved in a wreck on I-40 westbound. The semi, owned by Chalich Trucking, was bringing explosives from the McAlester Army Ammunition Plant in McAlester, Okla.

OKLAHOMA CITY — A tractor trailer rig carrying 28,000 pounds of explosives from the McAlester Army Ammunition Plant in McAlester crashed and overturned Wednesday on Interstate 40 in Oklahoma City.

Westbound lanes of the interstate were shut down just past the interchange with Interstate 35 and traffic was being diverted onto I-35 northbound, according David Meuser, spokesman for the Oklahoma Department of Transportation. Eastbound lanes of the interstate remained open.

Deputy Fire Chief Cecil Clay said officials are waiting for the military to give authorization for the load to be checked. He described the collision as minor and said there were no major injuries.

"We had to shut the highway down there because we don't have authorization to open up that trailer to make sure the load hasn't shifted. If the load is shifted, it could cause an explosion," Clay said.

McAlester Army Ammunition Plant spokeswoman Charity Prather said the accident is under investigation and had no further information or comment.

Oklahoma Highway Patrol Capt. Chris West said the semi is owned by Chalich Trucking, Inc. A man who answered the phone for the trucking company would not confirm or deny that its truck was involved in the accident and hung up.

The company's website says it is based in Ramsey, Minn.

The late Wednesday morning collision occurred when a van collided with the semi, according to West.

"The van driver was not paying attention, perhaps fiddling with something inside the van, and hit the semi," West said.

Emergency Medical Services Authority spokeswoman Lara O'Leary says one person was taken to a Midwest City hospital in good condition. O'Leary had no other details.