A massive carbon monoxide leak at Building Blocks Daycare in Kittery left seven children hospitalized on Wednesday, along with four adults.

The Kittery Fire Department received a call at around 3 p.m. on Wednesday afternoon, reporting a carbon monoxide incident involving 27 children and ten staff members in the building.

Emergency services from Kittery responded to the scene and found the victims reporting nausea and headaches.

Seven of the children had symptoms severe enough to warrant ambulance rides to the Portsmouth-area hospital.

Four staff members also drove themselves to the hospital for treatment.

All the victims are expected to recover.

State Fire Marshal Shawn Esler is currently investigating the cause of the carbon monoxide leak, and the daycare is expected to stay closed during the investigation.