On Tuesday evening, Bharat Narumanchi took several people hostage at a children's clinic in Austin, Texas, but except for a doctor the others escaped or were let go, local police said in a statement on Wednesday.
Hostage negotiators tried to contact him and when that failed, a police SWAT team entered the building and found him and Katherine Lindley Dodson, the doctor held as hostage, dead from "apparent gunshot wounds", according to the police.
"It appeared that Narumanchi shot himself after shooting Dodson," the police said.
According to the hostages, Narumanchi had visited the clinic a week ago seeking a volunteer position.
Mystery surrounds the incident as it did not appear that the Indian-origin man had any relation or other contacts with his victim, according to police.
"We feel like his terminal cancer probably played a large part in whatever it was that occurred in his life and what was happening yesterday," Police Lt. Jeff Greenwalt was quoted by TV station KXAN as saying.
He appealed to Narumanchi's friends and relatives to provide any insights into his behaviour.
When Narumanchi went to the clinic on Tuesday, he was armed with a pistol and what appeared to be a shotgun, according to the hostages interviewed by police.
Healthgrades.com reported that Narumanchi, 43, studied medicine at on the island of Grenada and had worked at an Army medical centre in Hawaii.
He was also on the list of doctors at two hospitals in Santa Ana, but the details about him were removed.
According to news reports, Narumanchi had a chequered background.
KXAN said that his services had been terminated by a New York hospital after a year and a half and he had filed a case against the hospital.
The Austin American-Statesman newspaper reported that he had been charged with domestic abuse in Hawaii, but the case was dropped.
He had divorced his wife and they had a custody battle in court over their child, according to the newspaper.
Dodson, 43, was the mother of three children, according to the newspaper.