PRATT, Kan. (KAKE) - A woman in her 30s and two children believed to be from Wichita have died following a crash Tuesday morning near Pratt.

It happened at around 10:50 a.m. on U.S. 54 at mile marker 136, which is just west of Pratt. Trooper Chad Crittenden with the Kansas Highway Patrol said the crash involved a Nissan SUV and a semi hauling a trailer full of sand.

Trooper Crittenden said the semi was stopped due to construction and attempting to merge when the SUV struck the rear of the tractor-trailer. The woman and one juvenile in the SUV died at the scene, and the second juvenile died a short time later. The three are believed to be related. 

"We don’t know why this happened," Crittenden said. "From this point, it doesn’t look like the vehicle had slowed down prior to the crash, as it rear ended the commercial motor vehicle. There were three occupants of this SUV. Unfortunately, all three were killed in this crash.”

The woman's identity is expected on the patrol's crash log at a later time, but KHP said additional information about the juveniles will not be released. Troopers tell KAKE the woman was not wearing a seat belt at the time of the accident, but the children were.

Crittenden said, “We just ask everyone to buckle up, pay attention, and put the phones down. Anything we can do to be safe out here.”

It is days with good weather that can often catch drivers off guard.

“It’s sad but a lot of folks think that crashes happen when the weather is bad and different things like that but unfortunately we kind of get more complacent, all of us do as drivers out here and these clear dry days that’s when things can happen quickly out here,” he said.

The tractor-trailer driver was not hurt. 

Both directions of U.S. 54 were closed between Pratt and Wellsford as crews worked to clear the scene. The highway was closed for about four hours, but it is back open as of 2:40 p.m.