Washington, Jan 7 

At least five persons were killed after a gunman opened fire at the Fort Lauderdale-Hollywood International Airport in Florida on Friday, officials said.

The gunman was identified as Esteban Santiago-Ruiz, 26, who had active-duty military identification on him and was born in New Jersey, law enforcement sources told CBS News. 

Federal law enforcement officials told CBS News’ Jeff Pegues that Santiago-Ruiz had gotten in an argument on one leg of his flight from Alaska to Florida, and the second leg of the trip was on a Delta flight.

The motive for the attack is yet to be known, according to law enforcement officials, CNBC reported.

In Nov. 2016, Santiago-Ruiz walked into an FBI office in Anchorage and claimed he was being forced to fight for ISIS, law enforcement sources told CBS News. He also said his mind was being controlled by the CIA to watch ISIS videos, sources said. He was sent to a psychiatric hospital after police were called, sources said. 

He was also investigated as part of a child porn investigation in either 2011 or 2012, law enforcement sources told CBS News. Three weapons and a computer were seized, but no charges were filed, sources said. 

All flights were grounded and additional areas of the airport were being evacuated. 

The Broward County sheriff's office tweeted that there were unconfirmed reports of additional shots fired on airport property and it was conducting an active search.

President-elect Donald Trump and Vice President-elect Mike Pence tweeted about the situation.

Trump tweeted: "Monitoring the terrible situation in Florida. Just spoke to Governor Scott. Thoughts and prayers for all. Stay safe!" 

"Our thoughts and prayers are with the victims, their families and our first responders in Fort Lauderdale, FL," Pence wrote on Twitter.

In a news conference, the law enforcement officials said the situation was "fluid and active". They confirmed the shooter was unharmed and in custody. Law enforcement did not fire any shots, officials said.

The Transportation Security Administration warned people at the Fort Lauderdale Airport to shelter in place and described it as an active shooter situation.

The airport tweeted the shooting, in which five persons lost lives, took place at the Terminal 2 baggage claim area in the lower level. It said the airport would be closed for an extended period of time.

Hundreds of passengers and airport workers could be seen gathering and evacuating via the tarmac.

The airport has four terminals and serves more than 73,000 travellers every day. It ranks 21st in the US in total passenger traffic, with more than 650 commercial flights a day.