CHICAGO — Two people in the Chicago area may have died from heat-related causes on the Fourth of July, pending further investigation into the official cause of death.

A spokesman for the Cook County medical examiner's office says the two deaths Wednesday so far are the only fatalities possibly related to the recent wave of roasting temperatures.

The National Weather Service has issued an excessive heat warning for Chicago through Friday at 6 p.m. That means the area is expected to see dangerously hot temperatures for a prolonged period.