Story highlights A note from the detained boy tells his parents he is OK and not to worry, an uncle says

Tariq Khdeir, 15, was born in the U.S. and is a high school sophomore in Tampa, Florida

He was visiting his Palestinian relatives for the first time in over a decade

Israel's Justice Ministry says it will investigate the beating

A Florida resident and cousin of a Palestinian teenager killed in Jerusalem this week is the young man seen in separate videos being held down and pummeled by men in the uniform of Israeli security forces, relatives said.

Tariq Khdeir, 15, a high school sophomore in Tampa, was visiting his Palestinian relatives in Jerusalem for the first time in over a decade when he was attacked and detained, family members told CNN.

Tariq, born in Baltimore, was outside the home of his cousin, who was kidnapped and killed on Wednesday in an incident that has further stoked tensions between Palestinians and Israelis. The tensions already had risen sharply after three Israeli teens were found dead in the West Bank.

The two videos, which were posted independently, say the beating occurred on Thursday.

In Tampa, Tariq's aunt, Sanah Abukhdeir, said the boy was visiting his grandmother, who is on her deathbed.

The teen's mother identified him in the video by the clothing he was wearing, including an Ecko T-shirt, his aunt said.

"Send our boy home," she said, expressing concern about the medical attention he was receiving. "He's pure American."

An uncle who is in regular contact with the boy's parents said the family was told Tariq was shackled to a hospital bed. After being treated in a hospital, he was moved to a detention center.

"It's unbelievable how they kicked him," the uncle said of the beating.

Tariq is a typical teenager who takes lots of selfies and enjoys fishing, according to his family. Among his friends, his nickname is "Fish," after his favorite hobby.

'A very serious incident'

The Israeli Defense Forces issued a statement Saturday seeking to distance themselves from the beating.

"It seems that the Israel Police Forces were involved in the incident, and not the IDF Forces," the statement said.

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In a statement, the Justice Ministry said the government's legal adviser will investigate the videotaped beating in the Shuafat neighborhood.

Israeli Justice Minister Tzipi Livni is quoted in the statement as saying the images "show a very serious incident by uniformed personnel, while this is not the Israeli's law enforcement policy -- yet sadly, they are the ones headlining worldwide news."

'Am I going to hear him screaming?'

CNN's Ben Wedeman spoke to Tariq's mother, Suha Abu Khdeir, who said she just couldn't watch the video of the beating.

"I don't want to see the video, I don't want to hear the video," she said. "I don't want to hear it. I don't know what I am going to hear. Am I going to hear him screaming? Am I going to hear him calling for help?"

She said she visited her son in the hospital, but he remains in custody. She did not know why he was arrested.

She and the boy's father, Salah Eddeine Abu Khdeir, said the teenager was among people protesting the death of his cousin, but wasn't involved in the clashes with Israeli security forces.

"I asked my son, 'Did you throw rocks?' He said no," his father said.

"He didn't have to throw rocks, he's just a Palestinian, in front of his neighborhood, hanging out with his relatives," Tariq's mother said.

Complaints of rough treatment

Palestinians have long complained of rough treatment by the Israeli police and double standards when it comes to justice, says Bill van Esveld of Human Rights Watch.

"The concern is that we've got plenty of evidence that this child of 15 was brutally beaten by Israeli law enforcement," van Esveld told CNN. "And instead of the law enforcement officials responsible for the beating being questioned and detained, the child who is the victim is being questioned and detained."

One neighbor shot a video of the beating and distributed it to family and a television station. Another video was shot from the other side of the street and posted to YouTube.

Relatives watched the video and told CNN that the teen is Tariq Khdeir. Relatives released pictures of the bruised teenager with swelling on his lips and nose.

The men delivered more than 20 blows to the youth over a period of two minutes. He did not appear to be struggling and police carried away his limp body afterward.

Both videos start after the incident began, and it's not clear why Khdeir was attacked.

'That should not happen'

Mark Regev, spokesman for Israeli Prime Minister Benjamin Netanyahu, said he had seen the videos on CNN.

"I think people who have that video should take it straight to the Israeli police," he said. "There is a separate department in our Ministry of Justice who will investigate that sort of thing."

Regev said he did not know the details of this case. "That should not happen," he said. "Obviously, it is forbidden under Israeli law to beat up a suspect who is in handcuffs."

"It's attempted murder," Suha Abu Khdeir said of her son's beating.

Calls for U.S. to intervene

Khdeir's father told CNN that a U.S. consular officer visited the teen in a Israeli detention center in Jerusalem. The officer told Khdeir's father that the teen does not remember much of what happened during his arrest.

The officer passed on a note from Tariq in which he said he was OK and told his parents not to worry about him, according to the uncle who is in regular contact with the parents.

U.S. State Department spokeswoman Jen Psaki called the reports "troubling" and called for a "speedy, transparent and credible investigation and full accountability for any excessive use of force."

The Council on American-Islamic Relations urged the United States to help free the teen.

"It is the duty of American officials to intervene and secure the release of an American citizen who was so viciously attacked," said Hassan Shibly, executive director of CAIR-Florida.

Khdeir is expected to appear at the Jerusalem magistrate court at 11 a.m. Sunday (4 a.m. ET), according to his father.

His cousin, Mohammed Abu Khedair , who was abducted and killed in Jerusalem this week, died from being burned alive and hit on the head with a blunt object, according to Palestinian General Prosecutor Mohammed al-Auwewy, citing a medical autopsy.

Al-Auwewy said the autopsy discovered traces of smoke inside the lungs of the 16-year-old, indicating that it was inhaled while the fire was burning.

After the teen's funeral on Friday, more than 60 people were injured in clashes with Israeli security forces in parts of Jerusalem, according to the Palestinian Medical Relief Society, a group that said it was involved in evacuating injured Palestinians. It said the injuries mostly involved rubber bullets fired at the upper body and chest.