LOS ANGELES, California — The mother of a boy taken into custody Thursday. A non-verbal boy found alone at Union Station Wednesday night after he was reunited with family, police said Thursday.

The case is being investigated by detectives, why the boy, who was initially thought to be deaf, was left alone at Union Station. Police later said the nonverbal boy was thought to be deaf because they couldn’t communicate with him, even via a sign language interpreter.

According to LAPD, the boy’s 31-year-old mother was arrested on suspicion of felony child endangerment.

The boy was found outside a cafe at about 7 p.m. in the downtown Los Angeles transit hub. Cafe Crepe employees said that around 5:30 p.m. they saw a woman with the boy after which she left the child about 30 to 40 minutes later, so they notified police and security.

“He was still smiling,” said Adrienne Garrett, who tried talking to the boy. “He was still running up and down here. What got my attention is he tried to go inside the restaurant.”

Garrett said she and other cafe employees tried to get the woman’s attention, but she ignored them and walked away.

While with police, a sign language interpreter was unable to communicate with the child. After someone recognized the boy on the news, his family was contacted by police.

Police say his biological mother returned to Union Station just before 2 p.m. and was taken into custody. The investigation is ongoing.

Police said the power of social media helped solve the mystery, but questions remained Thursday.

If you have any additional information about the incident, you are asked to contact the Transit Services Division at 213-922-1410 or 877-527-3247.