A horrifying video posted online appears to show Israeli police beating a Palestinian-American teenager, shortly after his detention amid protests that were spawned by the murder of his cousin.

Tariq Khdeir, a 15-year-old U.S. citizen from Florida, is a cousin of Mohammed Abu Khdeir, the Palestinian 16-year-old whose abduction and murder has triggered days of protests and riots.

The State Department confirmed Saturday night that Khdeir was being held by Israeli authorities. Spokeswoman Jen Psaki said the U.S. is "profoundly troubled" by reports he was beaten and called for a thorough and quick investigation.

"We are profoundly troubled by reports that he was severely beaten while in police custody and strongly condemn any excessive use of force. We are calling for a speedy, transparent and credible investigation and full accountability for any excessive use of force," Psaki said in a statement.



"We reiterate our grave concern about the increasing violent incidents, and call on all sides to take steps to restore calm and prevent harm to innocents."

The video posted online appears to show two Israeli policemen punching, kicking, and stomping on the person they had taken into custody.

A police spokesman, Micky Rosenfeld, said Khdeir had "attack[ed] security officers," according to The New York Times. The boy's father, Salah Abu Khdeir, told The Associated Press his son denied the allegations.

"I asked my son, 'Did you throw rocks?' He said, 'No,'" Salah Abu Khdeir told CNN in an interview. The boy's mother told ABC in an interview that he was "unrecognizable" after the alleged beating.



Khdeir's family released before-and-after photos of him to the media:

American teen, cousin of murdered Palestinian, in Jerusalem hospital. Parents say was beaten by police in #Israel >> pic.twitter.com/VWdMZQNSCI — Jon Williams (@WilliamsJon) July 5, 2014

Israeli police arrested a "number" of suspects in the brutal killing of Mohammed Abu Khdeir on Sunday, and an official told The Associated Press authorities believe the killing was "nationalistic" in nature. He was abducted last week, and his burned body was found days later.

Watch the video of police allegedly beating Khdeir: