In this illustration picture taken in Paris on November 14, 2015 a person holds aloft a smartphone bearing the message 'Je Suis Paris' in front of the Eiffel Tour, following a series of attacks on the city in which at least 128 people were killed. JOEL SAGET/AFP/Getty Images)

Chaos gripped Paris Friday evening when militants began a deadly rampage in the French capital, launching seven apparently coordinated attacks. In the day following, a clearer picture emerged of how the attacks unfolded, but some major questions still remain unanswered about the worst terrorist attack in Europe in the last decade.

What we know:

What happened?

There were seven nearly simultaneous attacks: suicide bombings and shootings at multiple restaurants and stadium Stade de France, as well as a mass shooting at a Eagles of Death Metal concert at music venue Bataclan, where 200 people were held hostage. They all happened at or around 9:20 p.m. local time.

What is the death toll?

Friday's attacks killed at least 129 people and injured more than 350, according to multiple reports.

Who are the victims?

About 100 people were killed in the slayings at the Bataclan concert hall in Friday, where the band Eagles of Death Metal were performing. The band's merchandise guy Nick Alexander, from Britain, was one of the casualties. “It is with huge sorrow that we can confirm that our beloved Nick lost his life at the Bataclan last night,” said a statement from his family. Thomas Ayad, 32, a producer and manager for Mercury Music Group, and Elodie Breuil, a 23-year-old student, also died at the concert, according to Time.

Gillame Decherf, a 43-year-old writer for French magazine Les Inrocks, and Alberto Gonzalez Garrido, a 29-year-old engineer from Madrid, were also among the casualties at the Paris concert hall, according to the Associated Press. Djamnia Houd, 41, who worked for designer Isabel Marant, was killed at one of the cafes attacked.

The first American victim to be identified was Nohemi Gonzalez, a Cal State University-Long Beach student studying abroad in Paris, according to the university. The 20-year-old junior was killed at a restaurant.

A second American killed was identified as Lalo Salines, according to CNN. It is not clear where she was killed or how old she was.

How many attackers were there?

There were at least eight attackers involved, and officials believe that the assailants acted in sets to commit the series of attacks. Ismaël Omar Mostefai and Abbdulakbak B. have been identified as two of the eight attackers. Mostefai is reportedly a 30-year-old French national, and his father and brother are being held by authorities on suspicion, according to French media.

Who is responsible?

Islamic State group (ISIS) has claimed responsibility for the attacks. The group released a statement that called Paris "the city of abominations and peversion." See the full statement here. President Francois Hollande has also accused the group of being behind the attacks.

Why Paris?

France has one of the largest Muslim populations and become a hotbed for Islamic extremism, because of its open-border policy for refugees from the Middle East and North Africa. There are 442 French nationals or residents believed to be fighting with ISIS in Paris, according to a July report.

What we do not know:

  • The identities of all of the attackers has not been released. We do not know if they were all French nationals or if they were in the country under other circumstances.
  • It is not known how France, the U.S. and others will respond to the attacks. Obama said at a press conference Friday that the U.S. will stand in solidarity with France as one of its oldest allies. "We’re going to do whatever it takes to work with the French people and with nations around the world to bring these terrorists to justice, and to go after any terrorist networks that go after our people," he said.

For a comprehensive look at how Friday's tradegy unfolded, see our in-depth story here.