By Letitia Stein

TAMPA, Fla. (Reuters) - The gunman who killed 49 people at a gay nightclub in Orlando in the worst mass shooting in modern U.S. history has been buried at a Muslim cemetery in southern Florida, media reported on Thursday.

A state death certificate lists Omar Mateen's burial site as the Muslim Cemetery of South Florida in Hialeah Gardens, a city in Miami-Dade County, according to the Orlando Sentinel.

Mateen, 29, was killed by police after he took hostages during a three-hour standoff inside the Pulse nightclub. He also wounded 53 people in the June 12 attack.

A funeral home located at the same address as the cemetery carried out the arrangements, the state document showed. It did not give Mateen's cause of death, the Sentinel reported.

The cemetery could not immediately be reached for comment.

Mateen, a U.S. citizen born in New York to Afghan immigrant parents, claimed allegiance to the leader of the Islamic State militant group in a phone call with authorities during his rampage.

U.S. authorities believe that Mateen, who lived in Fort Pierce, Florida, with his wife and young child, was self-radicalized and acted alone without assistance or orders from abroad.

The massacre took place during a Latin night celebration at Pulse, which was planning a Latin night street party on Thursday to benefit employees of the club. Pulse has been closed since the shooting.

Several media organizations filed a lawsuit on Thursday seeking to force the city of Orlando to release 911 calls and other communications relating to the attack.

Noting the massacre was the latest in a series of mass shootings in the United States, the lawsuit said there was a strong public interest in fully evaluating how police and other first responders reacted during the most critical phases of the tragedy.

"Information gleaned from the actual conversations with Mateen and others lies at the core of understanding exactly how events unfolded and will provide critical insight into the propriety of the government's tactical response," the suit said.

On Monday, the Federal Bureau of Investigation released a partial transcript of a 911 call made by Mateen from the club, and gave brief summaries of three other calls by the gunman.

(Reporting by Letitia Stein; Editing by Daniel Wallis and and Peter Cooney)