Debris and crumpled trucks litter the ground Saturday in Haywood, Okla. The small town was hit by a tornado that damaged several homes in Pittsburg County, Okla. The National Weather Service office in Norman confirmed that a tornado touched down in Pittsburg County before briefly passing through the southwest side of McAlester. Deadly storms also hit Missouri.

Kansas City, Mo. ? Thunderstorms and tornadoes tore across the nation’s heartland Saturday evening, killing at least 18 people, mangling buildings and trapping people in rubble in areas still reeling from other recent bouts with severe weather.

A twister killed at least six people in the northeastern Oklahoma town of Picher, then skipped over the Missouri state line to wreak further death and destruction, authorities said.

The death toll in Oklahoma could climb, said state Emergency Management spokeswoman Michelann Ooten. The Picher tornado caused major damage in a 20-block area, she said.

“I know they are going through the rubble, trying to find people missing,” she said. “There are numerous injuries.”

At least 12 people were killed after severe storms spawned tornadoes and high winds across sections of southwestern Missouri Saturday, the State Emergency Management Agency said. Ten of the dead were killed when a twister struck near Seneca in Newton County.

The 11th fatality was reported north of Purdy in Barry County after a tornado hit there, the National Weather Service said. In Jasper County, a 17-year-old girl died near Carthage after heavy winds knocked a tree onto a trailer, said Capt. Tom Nixon of the Carthage Fire Department.

“They’re going over the hard-hit area and turning over everything and looking,” SEMA spokeswoman Susie Stonner said of emergency workers’ search for victims and assessment of damage. “It’s hard to do in the dark.”

The number of injuries across the area was not immediately available, though The Joplin Globe reported that more than 90 people from the region were being treated at Joplin hospitals.

The tornado near Seneca was reported shortly after 6 p.m. Saturday. The storm in Jasper County occurred about 20 minutes later.

The first twister apparently started near Chetopa, Kan., crossed the state line east of Baxter Springs and bore down on an area near Iris Road and BB Highway northeast of Seneca, NWS meteorologist Bill Davis told The Joplin Globe.