JACKSON, Miss. (AP) — This heat wave isn’t just stifling — it’s deadly.

Extreme temperatures continued Thursday across a large swath of the country, killing more than a dozen people, at least two police dogs and likely contributing to the death of Franklin the rhinoceros at a Mississippi zoo.

Arkansas fire departments were volunteering to hose down overheated cattle, and people as far north as Maine were trying to stay cool.

High school football teams and marching bands practiced indoors or canceled altogether.

Tennessee election officials touted air-conditioned polling places as a way to bring in voters, and many cities set up cooling centers for those who needed a break from the sun.

Residents were encouraged to check on their neighbors, especially the elderly.

The scorching temperatures and high humidity made it feel like at least 100 degrees in many places, with heat advisories in effect for 18 states.

“This heat wears on everybody,” said Sandy Shamburger, who runs Rankin Sod Farm in Brandon, Miss.

“We rigged up lights on a sod harvester so we can work at night.”

Still, not even nightfall brings much relief, with temperatures sometimes lingering in the 80s overnight.

In Columbia, S.C., 33-year-old Kylin Doster tried to stay under the shade of his umbrella stand as he hustled to serve up steaming hot dogs. He said he works from 10 a.m. to 3 p.m. on Main Street, then sets up outside a biker bar north of town from 11 p.m. to 3 a.m.

“It’s really, really hot now, but it even stays hot at night,” Doster said. “It don’t make any difference. It just stays hot.”

The heat has been blamed for at least 16 deaths in Mississippi and Tennessee alone, including a man who had a heart attack while mowing his lawn and a construction worker who was spreading concrete. Maryland authorities on Thursday reported two heat-related deaths from early last week.

Two concrete sections of U.S. Highway 49 in central Mississippi buckled Tuesday, when temperatures hit 103 degrees.