Five possible heat-related deaths, all involving people 60 years or older and having pre-existing medical conditions, have been reported by health officials in three states, underscoring the danger posed to those most vulnerable in the searing heat wave that has gripped much of the eastern United States for nearly two weeks.

See also: East Coast warned of heatwave.

Medical examiners said a 69-year-old nursing home patient was left outdoors in his wheelchair, unchecked, for more than three hours Tuesday during record heat in Milwaukee, CNN affiliate WISN reported.

Martin Belkin, a patient at Sunrise Care Center, asked to be wheeled outside at 2:45 p.m. and was found unresponsive at 6 p.m. by workers at the facility. His temperature, taken nearly two hours after he was discovered, was 101.4, according to The Milwaukee County Medical Examiner's Office.

Milwaukee had a record high temperature of 97 degrees on Tuesday, and a heat advisory had been issued the day before, warning of extreme heat between noon and 8 p.m. on Tuesday, WISN reported. The station reported Belkin also suffered from a number of medical conditions and had been in the hospital in recent months.

An autopsy has been performed, and a ruling on cause of death is pending further toxicology testing, which may take several weeks, said Karen Domagalski of the medical examiner's office.

Two deaths also were reported in Maryland and two in Tennessee.

In Maryland, two senior residents, ages 65 or older, have died in the past 10 days from excess heat exposure, according to the state's Department of Health and Mental Hygiene. Both of the affected residents, a Cecil County man and an Anne Arundel County woman, had underlying medical conditions, the health agency said.

Two deaths related to the heat were reported in Shelby County, Tennessee, county health department spokeswoman Heather Reynolds told CNN. A 75-year-old woman was found dead in her home on Monday, and a 60-year-old man who fell from his wheelchair in Tipton County was transported to a hospital in Shelby County, where he died Tuesday,

The woman had a working air conditioner that wasn't turned on, and none of her windows were open, Reynolds said. She had only a fan on. The Shelby County chief medical officer said the woman had a number of medical conditions, including hypertension, but heat was listed as a contributing factor.

The Tipton County man was an amputee who had diabetes and was overweight. He was apparently in his wheelchair on a ramp to his van when he fell. Neighbors passing by alerted emergency services, and he was taken to Tipton County Hospital before being brought to Shelby County.