U.S. Customs and Border Protection (CBP) on Tuesday said authorities are investigating an alleged sexual assault that took place in a border protection center in Arizona after a complaint from a detained underage migrant.

According to NBC News that has obtained an internal report, the 15-years-old girl from Central American country Honduras said a CBP officer put his hands inside her bra, pulled down her underwear and groped her under the guise of a routine pat-down search.

The victim also reported that the officer has embarrassed her in front of other migrants, while his fellow officers were watching and laughing as well.

Washington Post reported that CBP confirmed that the case is investigated.

“The allegations do not align with common practice at our facilities and will be fully investigated,” the CBP spokesman said in a statement to Washington Post.

“It’s important to note that the allegation of sexual assault is already under investigation by the Department of Homeland Security’s Office of Inspector General.”

Sexual assault and harassment is the latest of horrible treatment of migrants at U.S. detention centers at the border.

United Nations High Commissioner for Human Rights Michelle Bachelet said she was “deeply shocked” by the conditions, referring to overcrowded centers that neglects event the most basic needs of detained migrants.

“As a pediatrician, but also as a mother and a former head of state, I am deeply shocked that children are forced to sleep on the floor in overcrowded facilities, without access to adequate healthcare or food, and with poor sanitation conditions,” Bachelet’s office said in a statement.

Droves of migrants from Central America trek hundred of miles each year to cross treacherous deserts and rivers on their way to the U.S., in a bid to flee violence and poverty in their home countries.