The FBI has joined the search for a 2-year-old Washington state boy who was last seen by his mother inside a parked car.

Sky Metalwala was reported missing Sunday morning after his mother discovered him missing from her car in Bellevue, Wash.

The child's mother, Julia Biryukova, told police that she had run out of gas and left the boy buckled into his car seat while she and her 4-year-old daughter walked to a Chevron gas station, about a mile away. 

When the pair returned to the silver Acura approximately an hour later, the 2-year-old boy was gone, Fox affiliate KCPQ-TV reports. 

The woman reportedly told police that the car was not locked.  

The toddler is of Indian and Caucasian descent, with brown eyes and dark hair, according to police. He was reportedly last seen wearing a dark green hooded sweatshirt and blue and gray-striped pants.

Biryukova was interviewed by detectives Sunday night, while the 4-year-old girl was being looked after by family members, according to the station.

The woman had previously been cited for leaving a child unattended in a vehicle. In 2009, Redmond police cited Biryukova and her husband, Solomon Metalwala, for leaving a child unattended in a vehicle. The case was dismissed after they agreed to probation, community service and a 10-week parenting class.

About 50 people, including police with tracking dogs, fanned out around the area Sunday in their search for the child, Bellevue police spokeswoman Carla Iafrate told the station. 

Iafrate said the boy's parents were cooperating.

Anyone with information on the boy's whereabouts is being urged to call 911.

The Associated Press contributed to this report. 

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