At least one gunman burst into a resort complex in Manila early Friday, opening fire with an assault rifle and setting fires in an ambiguous attack that initially ignited fears of terrorism in the Philippine capital. Authorities later expressed doubt that it was terror-related.

Several hours after the attack began at Resorts World Manila, Philippine National Police Chief Ronald Dela Rosa told reporters that a single gunman was believed to be responsible for the assault and was still at large. Dela Rosa said the attacker set fire to gaming tables in a casino at the complex by pouring gasoline on them but did not fire at people.

The resort said it was on “lockdown” following the attack, which it attributed to multiple assailants.

Philippine police, fire trucks and SWAT teams rushed to the scene at Resorts World Manila, where witnesses reported seeing a masked gunman firing at guests on the second floor of a hotel.

An upper floor of a nearby mall was on fire, and photos circulating on social media showed plumes of smoke pouring out of the building. Video footage showed people running out of the hotel amid billowing smoke.

The incident initially raised fears of a connection to fighting on the southern island of Mindanao between security forces and Islamist rebels linked to the Islamic State, who have taken hostages and burned buildings in a battle for control of the city of Marawi.

As authorities struggled to ascertain what was happening at the resort complex, there were conflicting reports on what motivated the attack and whether more than one gunman was involved.

“We have no official information as to the identity or affiliation of the persons responsible for this attack,” Resorts World Manila said on Twitter.

Dela Rosa told reporters there was no evidence that the attack was an act of terrorism.

Earlier, the SITE Intelligence Group, which monitors terrorist Internet activity, said a Filipino operative linked to the Islamic State claimed that “lone wolf soldiers” carried out the attack. There was no confirmation of the claim, and analysts have said that any connections between the Islamic State and Muslim insurgents in the Philippines are tenuous at best.

In Washington, President Trump began an announcement regarding the Paris climate agreement by saying he was closely monitoring “the terrorist attack in Manila.”

“It is really very sad as to what’s going on throughout the world with terror,” he said.

Resorts World Manila, in the southwestern part of Metro Manila near Ninoy Aquino International Airport, said on Twitter early Friday that it was “currently on lockdown following reports of gunfire from unidentified men.” It said it was working closely with police to ensure the safety of employees and guests, adding: “We ask for your prayers during these difficult times.”

Stephen Reilly, the resort’s chief operating officer, told reporters that hotel guests and staff were evacuated.

The large resort complex is popular with tourists and features hotels, restaurants, bars, a casino, a shopping mall and a theater.

Philippine news media reported injuries in the incident, but there was no immediate official confirmation. Witnesses interviewed on local radio stations reported varying numbers of gunmen.

One news channel, ANC, reported that there were two gunmen wearing masks and black clothes.

“I heard many, many gunshots,” Julio Silva, a witness who managed to dash out of the mall complex, told the DZMM radio network, the Associated Press reported.

A police spokeswoman urged the public to avoid the area. She said authorities’ main concern is to protect people trapped in the resort and police officers on the scene.

President Rodrigo Duterte responded to the violence on Mindanao last week by declaring martial law on the entire island of Mindanao. He has also threatened to impose military rule nationwide.

The fighting in Marawi broke out May 23 when Philippine troops attempted to capture Isnilon Hapilon, the leader of a terrorist group known as Abu Sayyaf.

Thousands of residents have fled the city, and at least 140 people have been reported killed there since the siege began last week.

Abu Sayyaf is best known for engaging in kidnapping for ransom, occasionally abducting foreigners from vacation spots in the southern Philippines. Some victims have been beheaded. Since February, the group has decapitated a German tourist, a Filipino fisherman and a Filipino soldier.

Hapilon declared allegiance to the Islamic State in 2014 and reportedly formed an alliance with other militants under the group’s aegis. But there has been little evidence of practical Islamic State involvement in the insurgency.