A heat advisory for the area has been extended for Wednesday, with heat indices as high as 110 degrees expected, the National Weather Service in Tulsa said.
The advisory is in effect from noon until 8 p.m. Wednesday for all of eastern and central Oklahoma.
High temperatures are expected in the low- to mid-90s again on Wednesday, but heat indices are forecast to be 105 to 110 degrees, forecasters said.
On Tuesday, when a heat advisory was also in effect, EMSA had responded to 11 suspected heat-related calls and transported 10 patients to local hospitals because of heat-related symptoms as of 8:30 p.m., an EMSA spokesman said.
"With extremely hot temperatures forecast this week, EMSA is urging citizens to make a plan to stay safe over the next several days," the agency said in a news release.
"Plan the amount of time you think will be outdoors and take appropriate amounts of water or other fluids with you, even if just planning for a short amount of outdoor time.
"Emergencies can happen and you could be stranded outdoors longer than expected. Always have a cell phone with you to call 911, if needed."