CHICAGO (CBS) — The third straight day of triple digit heat has led to the deaths of at least six people, authorities said on Friday.

Carmen Mercado, 81, died of heart disease and heat stress, according to the Cook County medical examiner’s office, which noted that there was no air conditioning in her room.

Riley Kimble, 59, died of heart disease, with heat stress a contributing factor.

Another elderly woman, 91-year-old Pat Wong, died of heart disease, with diabetes and heat stress contributing factors.

Frank Proczek, 58, died of heart disease, with chronic alcoholism and heat stress as contributing factors.

All four died on Thursday.

On Thursday, autopsies confirmed the first two heat-related deaths of the season in Cook County, 53-year-old Eugene Burns of Maywood and 48-year-old Jon McCullough, of the North Side Ravenswood neighborhood.

Thursday and Friday’s high temperature set a new record of 103 degrees, while Wednesday’s high was 102 degrees.

There were 16 heat-related deaths in Cook County in 2011.