US immigration authorities said Tuesday they are investigating a report of a border agent in Arizona sexually assaulting a 15-year-old immigrant girl.

The Honduran girl said a large, bearded officer put his hands inside her bra, pulled down her underwear, and groped her in front of other immigrants and officers during what was supposed to be a routine pat-down, NBC News first reported.

"Minor reports officer asked her to lift her shirt up to bra line and then he put his hands inside her bra and touched her breast," according to an incident report compiled by government case managers. "Minor reported she felt embarrassed as the office[r] was speaking in English to other officers and laughing."

The officer then allegedly pulled down her pants and touched her waist and pulled at her underwear. The girl said the officer then asked her to spread her legs and arms and "patted her down in a way that made her feel uncomfortable as she felt he groped her body, her breast and private parts as well."

A US Customs and Border Protection spokesperson said the allegation of sexual assault is under investigation by the Department of Homeland Security’s Office of Inspector General.

"The allegations do not align with common practice at our facilities and will be fully investigated," CBP said in a statement to BuzzFeed News.

The report is one of nearly 30 accounts compiled between April 10 and June 12 by case managers for the Department of Health and Human Services, which takes immigrant children from CBP custody and into its own facilities.

In those accounts, children held by CBP in the Yuma Sector also reported being denied phone calls, showers, or anything to sleep on, which resulted in some sleeping on concrete or outside with only a Mylar blanket to shield them from the cold. Other children complained about going to sleep hungry or having their sleeping mats taken away when they complained about the food and water.