ORLANDO, Fla. — With dozens of survivors of the massacre at a gay nightclub here still hospitalized, some of the wounded on Tuesday gave gripping accounts of terror and pain on a night that turned in an instant from joyous to deadly.

The survivors told of fleeing, hiding, using their phones to plead for help, watching friends die — and thinking that they would also — as a man with an assault rifle and a handgun went through the Pulse nightclub, firing more shots than they could count. The slaughter early Sunday left 49 victims dead, in addition to the gunman, and 53 wounded — the worst mass shooting in American history.

“The guilt of feeling lucky to be alive is heavy,” said Patience Carter, who was shot in the legs and saw her friend Akyra Murray killed. “I was begging God to take the soul out of my body because I didn’t want to feel any more pain, I didn’t want any more shots.”

More than 30 of the wounded remained in hospitals on Tuesday, including at least six who were in critical condition. All of the dead had been identified, and most of the autopsies were completed.

As the injured and the doctors who treated them told their stories, the F.B.I. continued looking into the actions of the gunman, Omar Mateen, 29, who died in a shootout with police, seeking evidence of a motive and any possible accomplices — in particular, whether his wife may have known he was planning the assault. His wife, Noor Zahi Salman, has told investigators that she once drove him to the nightclub, that she was with him when he bought ammunition, and that she tried to talk him out of mounting an attack, law enforcement officials said.

Mr. Mateen had voiced hatred of gays, minorities and Jews, and had claimed links to Islamist terrorist groups; during the siege at the nightclub, he declared allegiance to the Islamic State. But investigators were also looking into reports that he might have been gay himself.

His ex-wife, Sitora Yusufiy, said that Mr. Mateen had told her that he had frequented nightclubs before their marriage, but had not described them as gay clubs.