EMSA issued a heat alert for the Tulsa area Tuesday afternoon.
As of 4 p.m, EMSA said its medics had responded to six heat-related calls.
Of the six patients treated on Tuesday, two were transported to hospitals, according to EMSA. One patient was in heat-related cardiac arrest and transported in critical condition. One patient was in fair condition.
The agency issues a medical heat alert when it responds to five or more suspected heat-related illness calls in a 24-hour period.
EMSA urges people to be proactive about staying safe in the heat by keeping fluids accessible and drinking plenty of water before going outdoors and during outdoor time. The agency also recommends people limit outdoor time and take frequent breaks in shade or indoors.
EMSA said it was still on scene of two of the calls.