ISTANBUL, Turkey, June 28 (UPI) -- The U.S. Federal Aviation Administration suspended all U.S. flights to and from Istanbul Atatürk Airport in Turkey's largest city after a bloody terror attack killed at least 36 people and injured 147 others on Tuesday.
The airport was rocked by gunfire and bomb explosions in what appeared to be a coordinated militant attack, witnesses and authorities said.
Turkish Prime Minister Binali Yildirim said early signs indicate the Islamic State militant group might be behind the attack. No group has claimed responsibility.
Turkey's Justice Minister Bekir Bozdag said at least 147 people were injured.
Authorities said police started shooting at the suspects to keep them away from the secure area of the terminal when they set off their explosives. The attack happened around 10 p.m.
"I was going from the domestic to the international terminal, then there was suddenly a fireball and I saw people covered in blood," a taxi cab driver said.
Turkish Justice Minister Bekir Bozdag, who said he knew which terror group was responsible, noted that one attacker fired an AK-47 assault rifle at people near him before detonating a suicide vest.
A senior Turkish official and Istanbul Gov. Vasip Şahin said three suicide bombers launched the attack -- two near a security checkpoint in the international terminal and one in the parking lot.
Istanbul Atatürk Airport, Turkey's largest, was locked down in the aftermath of the attack as police investigated and incoming flights were diverted.
"I harshly condemn those who executed this terrorist attack, and those who gave the orders for it," Bozdag said.
"I hope the attack at the Atatürk airport will be a turning point in the world, and primarily for the Western states, for a joint struggle against terror organizations," Turkish President Recep Tayyip Erdogan stated, also saying the attack "revealed the dark face of terror organizations targeting innocent civilians."
Video: CBS Evening News
Tuesday afternoon, the FAA issued ground stop orders on all U.S. flights to and from the airport, various news media reported -- a routine action taken in locations that pose a specific threat to U.S. travelers' safety.
In March, the U.S. Department of State advised American travelers to exercise caution in Turkey due to heightened threats. The department reiterated that warning Monday.
Turkey has faced a number of terror attacks in recent months in a growing trend of violence carried out by Kurdish militants amid the civil war taking place in neighboring Syria. In December, one person was killed in an attack on a different Istanbul airport and several more died earlier this month in a bombing carried out by Kurdish militants.
Increased militant activity is also scaring tourists away. The nation saw a substantial drop in tourists for May, officials said, which was the biggest visitor slump on record, Bloomberg reported.