Transcript for This day in history: Jan. 1, 2017

2017 begins with a deadly terror attack and now an all out manhunt for the killer. Surveillance video showing the graphic images the very moment a gunman fires as he approaches the upscale club in Istanbul Turkey. In sight as hundreds of happily happy revelers. Ring in the new year a massacre. At least 39 confirmed fatalities and dozens more injured including one American. The State Department tonight issuing an urgent warning to American citizens in Istanbul telling them. To shelter in place stay indoors and the White House condemning what they called quote a horrific terrorist attack. It is a grim New Year's Day for a country repeatedly targeted by extremism. ABC's Alex mark court starts us off at the scene. This was the scene in Istanbul's popular upscale rain and nightclub at midnight. The party years dancing waving sparklers. Instead he's flying as the new year is wrong in. But just over an hour later surveillance video captures this ominous scene just outside the club. Bullets ricocheting on the street. People running for cover. From the opposite angle graphic video of a man dressed in black pointing his rifle. Authorities say the suspect killed a police officer and another person on the street before storming the club. The view from inside shows a gunman dressed in white wearing a hood. Authorities believe the attacker changed his clothes he stayed inside for seven terrifying minutes. Shooting at the crowd had gathered an estimated 600 people. He didn't feel about got my husband told me to get on the ground then a man came this woman says. On my left and right everyone was crying the smell of gunpowder was everywhere. Revelers reportedly jumped into the city's boss for its river next to the club desperate to escape. In the chaos when attackers slips away and tonight is still on the run and eyewitness captured this video of the immediate aftermath. A man's body lying in the street panic yelling as ambulances raced to the scene. Survivors crying embracing each other still dressed to celebrate. At least 39 people dead tonight including more than two dozen foreigners the club popular with tourists. Dozens more were injured including at least one American. News. Day and anguish son weeping over his father's casket. Authorities scramble to find the person responsible. Americans warned by the consulate to shelter in place. The US and Turkey are calling this a terrorist attacks so far there's been no claim of responsibility. But tonight Turkish police sources tell us they do believe that the shooter showed signs of being a trained ice this fighter. Cecilia. Alex mark are leading us up tonight they Q and that manhunt under way right now in a country targeted by several recent terror attacks nearly 300 people killed there in 2016 alone in June he will remember. Three suicide bombers stormed Istanbul's airport with assault rifles 44 people killed. In that attack nearly 150. Wounded and less than two weeks ago. Russia's ambassador to Turkey assassinated inside an art gallery the gunman yelling about Syria as he opened fire I want to now. Bring in ABC news contributor Stephen gan your former deputy assistant secretary of state we just heard. Alex is reporting there that Turkish police believe this most recent attack may have been carried out by trade ices fighter what clues are you seeing. It lead you to believe the same thing. To see it there is an internal domestic terror threat mostly from Kurdish separatists but in this case it's the target the gives us the indication it may be I asked. And that is the nightclub we've seen it in Bali we've seen it in Orlando we've seen it in Paris. It's this idea that it's a target it's a symbol of secular decadence. That makes it very attractive to Jihad. Colonel Ken your thank you.

This transcript has been automatically generated and may not be 100% accurate.