U.S. officials are searching their databases for known terror suspects and other materials to aid in the hunt for the gunmen responsible for the Paris shooting Wednesday. The Obama administration has looked into increasing U.S. security in response to the attack and U.S. officials are in touch with their French counterparts.

Three gunmen opened fire on the offices of a satirical newspaper Charlie Hebdo in Paris, which is known for producing Prophet Muhammad caricatures and lampooning Islam, and killed 12 people–two policemen and 10 journalists–before escaping. The gunmen reportedly spoke unaccented French and shouted “Allahu Akbar” before leaving the offices. “Allahu Akbar” is Arabic for “God is great.” This terror attack is the deadliest France has seen in decades.

France’s president referred to the attack as a “terrorist operation” and called it a “cowardly attack.” He added that the office has been threatened several times. In 2011, its offices were firebombed over its Muhammad caricatures. And in the winter 2014 edition of the al-Qaida magazine Inspire, a “chief” describing where to use a new bomb said that the first priority should be the U.S., then the U.K. and then France.

France has already put a security alert in place at the highest level. In addition, they have taken protective precautions at stores, media offices and houses of worship. They have also closed Paris schools and reinforced protection involving transportation. However, the office of the U.S. Embassy in France tweeted that they are not planning on closing the embassy in Paris despite reports that have been “misleading.”

The identification of the gunmen is currently a main priority. According to Fox News, investigators are plunging through terror databases. They are also set to look at closed-circuit television, crime scene evidence and the level of premeditation since the gunmen asked for individuals’ name at the scene. The other major priority is deciding whether the attack is just a portion of attacks to come or if it is an isolated attack.

Analysts are reportedly looking into members of al-Qaida, self-radicalized individuals, people who have traveled to Syria and received training from al-Qaida and AQIM.

A Department of Homeland Security official reportedly told Fox News that the situation is being monitored closely. The official said that DHS will adjust security to “protect the American people” if necessary.

Rep. Peter King, R-N.Y., expressed his trust in the French authorities. He also said that the terror attack should be a “wake-up call” for Congress not to cut DHS funding.

President Obama called France America’s “oldest ally” and stated that he has directed his Administration to help in any way they can to help “bring these terrorists to justice.” U.S. investigators are set to become more heavily involved, but only after a request from the French government. Government officials in France and Hollande planned a televised address to air nationally late Wednesday.

Supporters of militant Islamic groups showed their approval of the attack on social media. A Tunisian loyalist of the Islamic State Group and al-Qaida called the attack revenge against France that was well-deserved. On the other hand, the hashtag #JeSuisCharlie was trending Wednesday as people showed their support for the satirical publication and for freedom in journalism.