The city of Houston on Saturday opened new distribution centers to give out water as thousands of customers remained without power following severe storms blamed in the deaths of seven people in the region.

Houston hit a high of 91 degrees Saturday as the city and Harris County recover from tornadoes and 100 mph straight-line winds that struck with little warning on Thursday.

Seven deaths — four in Houston and three in unincorporated Harris County — have been blamed on effects from the weather, including from falling trees and a fire sparked by lighting.

Around 350,000 customers in Harris County, where Houston is located, were without power as of around 10:20 p.m. local time Saturday, according to tracking website poweroutage.us. At its peak, nearly 800,000 homes and business were without power after the storm.

“Our crews’ visual inspections and damage assessments of our infrastructure yesterday showed that we have a lot of hard work ahead in the coming days,” CenterPoint Energy’s Lynnae Wilson, senior vice president for the utility’s electric business, said in a statement.

CenterPoint, the utility company with the bulk of the outages, said Saturday night that it estimated about 80% of its impacted customers would have power restored by Sunday evening.

Three schools were damaged, one by a tree that fell into a classroom, another with around 12 windows shattered, and one that had a wall collapse in a classroom, Houston Independent School District Superintendent Mike Miles said Saturday.

Miles called the relatively few buildings damaged districtwide “a blessing.” A decision will be made Sunday whether there would be school Monday, and a lot will depend on the electricity situation, he said.

“Today and tomorrow will tell a lot about power at these schools,” Miles said.

Approximately 90 of the district’s more than 270 schools do not have power, he said.

Houston faces another warm day ahead, with temperatures in the upper 80s to low 90s heading into next week.

“If you are without power, and even if you are not…please make sure to practice heat safety by staying hydrated, take frequent breaks if working outside, and look before you lock!” the National Weather Service said in a forecast discussion.

Elsewhere in the country, storms and severe weather are a concern.

The central and northern Plains were forecast to get storms starting Sunday, affecting around 2 million people in Kansas, southern Nebraska and northern Oklahoma. The Kansas cities of Wichita and Topeka were among those that could see large hail and damaging winds.