(SBT24/7News) U.S. 31 south of Plymouth remained closed late Monday after a crash between two semi trucks released liquid petroleum gas in the area and caused the evacuation of nearby homes.

According to the Marshall County Sheriff’s Department, the crash occurred at 12:45 p.m. when the southbound gas truck, a 2007 International driven by 65-year-old Ennis Lester of Amarillo, Texas, slowed to a stop in the right lane at a point where a railroad track crosses the road just north of 14th Road near Argos.

Indiana law requires all trucks carrying flammable cargo such as LP gas to stop at railroad crossings for safety. Lester told investigators he had stopped to check for oncoming trains and had just let off the brake when another semi struck his truck from behind, causing his tanker truck to begin leaking.

The second truck, a southbound 2007 Freightliner driven by 47-year-old William Merchant, of Hopkins, Mich., struck the stopped tanker with sufficient force to crush the cab Merchant was sitting in, pinning him in the wreckage.

Emergency workers at the scene had to cut Merchant from the remains of his truck, a process that took several hours. Eventually, they were able to free the driver, who was airlifted to Memorial Hospital in South Bend with unspecified injuries.

Merchant’s condition was not available late Monday.

Immediately after the crash, emergency responders rushed to the scene to block off U.S. 31 in both directions. Initial reports indicated that the tank truck may have been hauling anhydrous ammonia, a chemical used in farming that can cause burns and lung damage if inhaled.

Although those reports proved to be false, officials evacuated homes located within a half-mile radius of the scene of the crash because of the danger posed by the escaping LP gas.

Marshall County Emergency Management Agency director Clyde Avery said a staging area was set up at the Plymouth Fire Department in case any of the evacuees needed shelter, but the majority of those who were forced to leave their homes were able to stay with family.

“We only had one person who needed a place to stay until they were able to go home,” he said. “The (American) Red Cross was able to make arrangements for that person.”

The accident created traffic tie-ups that persisted into the night. Northbound traffic from the highway was initially routed east on 14th Road, causing a long backup of trucks as they tried to negotiate the narrow country byway.

However, a detour route was eventually posted to take southbound traffic along Michigan Road through Argos, then west on Indiana 110 to U.S. 31. Northbound traffic was being routed east on Indiana 10 and north on Michigan Road.

Both detours remained in effect at 9:45 p.m. EST Monday. Avery said it was not known when the highway would be able to re-open, and said that police and fire units remained on the scene late Monday.

“They are down to a skeleton crew right now, but they are still working on it,” he said shortly before 10 p.m. Monday.

Agencies assisting the sheriff’s department included the Indiana State Police, Plymouth Fire and EMS, Argos Police, Argos Fire, Indiana Department of Transportation, and the Northern Indiana Public Service Co.