Tornadoes killed five people in central Oklahoma, including a mother and her baby, and menaced Oklahoma City and its hard-hit suburb of Moore, before the storm system tracked northeast early yesterday.
The US National Weather Service said the severe weather threat would shift into neighboring Illinois and Missouri, where Missouri Governor Jay Nixon declared a state of emergency on Friday.
The tornadoes struck just 11 days after a twister ranked as EF5, the most powerful ranking possible, tore through Moore and killed 24 people.
The mother and baby were killed on Friday while traveling on Interstate 40, just west of Oklahoma City, when their vehicle was picked up by the storm and they were sucked out of it, Oklahoma Highway Patrol spokesperson Betsy Randolph said.
The interstate was shut down due to the storm, with multiple crashes and injuries.
Two of the five deaths in Oklahoma on Friday occurred in Union City and one in El Reno, in rural areas west of Oklahoma City, said Amy Elliott, a spokeswoman for the state Office of the Chief Medical Examiner.
She could not confirm where the other deaths took place.
More than 40 people were being treated for storm-related injuries — including five in critical condition, among them a child, according to the Oklahoma-based Integris Health hospital system.
Meteorologists had earlier declared a tornado emergency for parts of the Oklahoma City metropolitan area, and at one point posted a tornado warning for Moore.
Moore had limited damage from the latest storm activity, a police dispatcher for the city said.
A tornado rampaged down Interstate 40 toward Oklahoma City, tipping over trucks and hurling hay bales, a witness said.
Television images showed downed power lines and tossed cars as the storm systems dumped at least 7.6cm of rain, stranding motorists in flood water.
“For reasons that are not clear to me, more people took to the roads,” Oklahoma City Mayor Mick Cornett said.