CHICAGO — Three children, who are United States citizens, were released to their parents after being detained by U.S. Customs and Border Protection for about 13 hours at a Chicago airport Thursday morning.

The girls, 9, 10 and 13, were detained around 3 a.m. Thursday morning at Chicago O’Hare International Airport after traveling with a cousin from Mexico. The cousin was not a U.S. citizen, but had all the necessary paperwork to be let into the country.

According to a Border Protection spokesperson, the family member arrived at the airport with the children and they said they deemed the man “inadmissible.” The children were then detained.

The spokesperson said they attempted to reach the children’s family members to pick up the children. Around 2 p.m., they said they were still waiting for a legal guardian to pick them up.

The children’s parents were from the area, but their citizenship may have come into question. Officials have not confirmed nor denied that information.

The parents hired an attorney who got a notarized letter saying the children could be released into their custody. The letter was not needed, and the girls’ mother was able to pick up the children without incident around 4:30 p.m. at the airport.

The Border Protection spokesperson said the children were provided food and drinks during their detainment.

Congresswoman Jan Schakowsky was at the airport and had questions about why the children were detained in the first place.