A 5-year-old child was in a car whose adult driver lost consciousness after he apparently overdosed on an opiate drug Sunday night in Portland’s Old Port, authorities said.

Deputy Fire Chief Terry Walsh said police and ambulance crews responded to a call around 8:45 p.m. that a man had backed his car onto a sidewalk in front of Ri Ra’s Irish Pub and Restaurant at 72 Commercial St.

Walsh said emergency responders administered Narcan – a medication used to reverse the effects of opioids – to revive the man.

Walsh said the Narcan worked effectively, and the man, who was said to be in his late 20s, was transported to Mercy Hospital for treatment.

But Walsh said the crews also found a child – he was not certain if it was a boy or girl – in the car with the driver. The driver may have been the child’s father. Walsh said the Portland Police Department is investigating the incident.

Lt. Gary Hutcheson said police will contact the child’s other parent, and most likely notify the Department of Health and Human Services since the incident involves a minor.

Hutcheson said the investigation has just begun and it was not clear what type of drug was involved. Hutcheson said Narcan can be used to counteract the effects of methadone, heroin or oxycodone.

The man’s name and condition were not available Sunday.