Lightning struck an Ohio prison during severe weather in the state on Tuesday, injuring 16 inmates – including one who had to be airlifted to hospital.

The prisoners were outside during the storm, moving between buildings after an evening meal.

Nine of the inmates have since returned to the correctional institution, while seven remain in hospital, including one who was in serious condition, the Ohio Department of Rehabilitation and Correction said.

Severe weather and flash flooding has ravaged parts of the US Midwest in recent days, generating tornadoes, strong winds and causing widespread power outages.

No staff were injured in the strike, the Ohio Department of Rehabilitation and Correction said in a Wednesday morning update on social media.

At least one of the inmates was airlifted by helicopter to hospital. Their condition has not been disclosed.

Ohio Governor Mike DeWine addressed the incident at news conference Wednesday afternoon.

While the prison’s policy is to keep inmates indoors in the event of storms, according to DeWine, officers did not think weather conditions indicated that a lightning strike was imminent. For that reason, the prisoners walked their “normal pathway” outdoors after they finished eating at a dining hall.

BBC News has contacted the prison.

The lightning strike hit amid severe weather conditions across the Midwest. The National Weather Service (NWS) issued flash flooding warnings across Ohio and Indiana, and confirmed that three tornadoes touched down in Chicago’s south suburbs on Tuesday.

Footage across the region shows homes with damaged roofs and downed trees from the derecho.

A derecho is a powerful, long-lasting thunderstorm that produces wind damage over a vast area. The region had recorded winds of up to 100 miles per hour (160 kmph), leaving a path of destruction and debris in its wake.

At least three deaths have been confirmed, including that of a four-year-old boy whose family’s mobile home in Indiana was struck by a tree.

An Indiana woman was killed in a home explosion during a period of powerful winds of more than 100 miles (160km) per hour, according to CBS news, the BBC’s US partner.

First response efforts were delayed as a result of the road conditions, said police captain Rob Maynard. He said that although they believe the storm played a role in the woman’s death, they are unable to draw final conclusions right now.

There were also several gas leaks as a result of the storm, which can be caused when large trees fall and disrupt underground infrastructure, Maynard added.

In Ohio, another individual died when first responders were unable to quickly reach them during a flooding emergency, said Ohio Governor Mike DeWine.

“This is a very dangerous weather situation,” DeWine said on Tuesday, while warning people to keep an eye on the news and use “common sense”.

The storms have caused extensive power outages across the region.

More than 290,000 customers were without power in Indiana on Wednesday afternoon, as well as more than 160,000 in Ohio and 130,000 in Illinois, according to a power tracker webpage.

“Now is the time to plan for severe weather and flooding!” the NWS said, while warning of severe wind gusts strong enough to knock down trees, branches and power lines.

The Federal Aviation Administration issued ground stops at major airports in the area due to thunderstorms, including Chicago’s O’Hare and Midway airports, which continue into Wednesday afternoon.