Authorities in the United States and the United Kingdom are looking for more answers after a hostage situation at a Texas synagogue over the weekend. Among the big questions that still need to be answered: what was the motive behind it?

“We will conduct an independent investigation, my evidence response team will be here to process the scene and a team from Washington will be here to conduct an independent investigation,” FBI Special Agent in Charge Matthew DeSarno said Saturday. The video above shows scenes from the investigation Sunday.

Authorities identified the hostage-taker as a British national named Malik Faisal Akram. The 44-year-old was shot and killed Saturday night, ending a 10-hour standoff. Authorities have declined to say who shot Akram, saying it was still under investigation.

Akram could be heard ranting on a Facebook live stream of the Saturday services, demanding the release of Aafia Siddiqui, a Pakistani neuroscientist convicted of trying to kill U.S. Army officers in Afghanistan. According to reports citing people who heard Akram on the live stream, Akram chose the Texas synagogue because it appeared to be the closest assemblage of Jews to a federal facility in Forth Worth, where Siddiqui is serving an 86-year sentence.

In addition to Akram, police in Manchester, England announced Sunday night that two teenagers were taken into custody in connection to the Texas synagogue hostage situation. In a tweet, Greater Manchester Police said its counter-terrorism policing unit “continues to assist the investigation… and police forces in the region are liaising with local communities to put in place any measures to provide further reassurance.”

The hostage situation caught the attention of world leaders in the U.S. and Israel. The video above also shows their reactions. President Joe Biden addressed it when talking to reporters Sunday. He called the situation an act of terror.

“I wanted to make sure we got the word out to synagogues and places of worship that we’re not going to tolerate this, that we have this capacity to deal with the assaults on particularly the antisemitism that has grown up,” President Biden said. Meanwhile, in a video message, Israel Prime Minister Naftali Bennett thanked U.S. law enforcement but warned about what the hostage situation could mean.

“This event is a stark reminder that the dark forces of anti-Semitism still exist. We must, and we will fight it,” Prime Minister Bennett said. “To the Jewish community in the U.S. and Diaspora Jewry around the world I say: you are not alone. We’re one family and we stand strong and united together.”