Survivors Recall Deadly Precision of Attackers as 129 Reported Killed in Paris 'Bloodbath'

Scores killed in simultaneous terror attacks in Paris.

Authorities in France said Saturday that 129 people were killed and 352 injured Friday in the string of terrorist attacks that rocked Paris and sent shockwaves of grief across the globe.

At least six crowded sites including a concert hall, an avenue packed with cafes and the area around a national soccer stadium were targeted in the apparently choreographed gun attacks and bombings.

Before the smoke had settled Friday, President Hollande vowed to lead a "merciless" war against those responsible.

On Saturday, it emerged that ISIS had taken responsibility for the attacks in a statement circulated on social media by Islamic State supporters.

Six attackers blew themselves up at some point after the attacks. A seventh was shot by French authorities.

As part of the chaotic attack, gunmen armed with AK-47s attacked a restaurant near Paris' Bataclan concert hall on Friday night, and are believed to be on the loose. 

Julien Pearce, a witness inside the concert hall, told CNN that masked gunmen fired randomly at concertgoers for 10 minutes. They were "very calm and very determined" as they silently shot at people, who were desperately trying to crawl to safety, he said.

As he left, he passed 20 or 25 bodies on the ground. While he was able to escape, some of his friends have messaged him to say they are still hiding inside. 

"It was horrible," he said. "It was a bloodbath."

He said gunmen began firing on the crowd near the end of the concert, while the band was still on stage. "They were all dressed in black," he said.

Read: NYPD Beefs Up Security in Crowded Areas in Wake of Paris Attacks

A doctor from a hospital near the string of restaurants where attackers shot diners and drinkers indiscriminantly told Le Monde the seige came out of nowhere.

"We were listening to music when we heard what we thought were the sounds of firecrackers...A few moments later, it was a scene straight out of a war. Blood everywhere."

The country's leaders took swift and severe actions: France's borders were closed, a state of emergency was declared and people were advised to stay indoors.

Explosions could be heard outside the Stade de France, the French national stadium, where France and Germany were playing a soccer match. Those explosions were believed to have been detonated by suicide bombers. 

Read: Paris Attack Puts World on Alert

Hostages were taken at the theater, where a performance by the California band Eagles of Death Metal was underway Friday night. Witnesses reported explosions and gunfire inside the hall. After a standoff that lasted for hours, police stormed the facility.

The band posted a note on its Facebook page: "We are still trying to determine the safety of all staff and crew. Our thoughts were with all of the people involved in this tragic situation."

Read: American Train Heroes Get France's Highest Award For Bravery

Police descended on the theater about 1 a.m. local time, using ladders to get inside.

The targets "are all places where people go to enjoy a Friday night in Paris," Patrick Klugman, the city's deputy mayor, said. 

He called the attacks "unprecedented."

In a tremulous voice, the deputy mayor warned citizens to stay indoors. "There are many dead people all over Paris, much more than what we know already," he said.

Emilioi Macchio, who was at a bar near the restaurant, told AP: "It sounded like fireworks." 

Witness video of victims shows screaming and chaos:

The sound of a massive explosion could be heard at the stadium. Hollande left the game to convene an emergency cabinet meeting.

"This is heart-breaking," American President Barack Obama said Friday night at a hastily called press conference. "France is our oldest ally."

The night of terror comes after at least three high-profile terror attacks in France this year.

In January, 12 were killed at the offices of satirical newspaper, Charlie Hebdo. A second attack unfolded one day later at a kosher grocery store, where four died.

In August, a group of American friends helped thwart a terrorist attack on a Paris-bound train.