Three students and a teacher were taken to hospitals Wednesday after a fire broke out during a demonstration in a Virginia high school chemistry classroom, officials said.

Dinwiddie High School released students early after school district officials said the fire alarm was pulled, and all students were evacuated from the building.

First responders, including police and at least two ambulances, were seen outside the school around 11 a.m., according to WRIC-TV.

Thursday is an "asynchronous learning day," officials said.

VIRGINIA HIGH SCHOOL EVACUATED AFTER CHEMISTRY CLASS ‘INCIDENT’

Dinwiddie High School

Dinwiddie High School was let out early after an unspecified "incident" in a chemistry class prompted an evacuation on Wednesday. (Google Maps)

A teacher was taken to a local hospital and three students were taken to VCU Medical Center, officials said. Officials didn’t release details of their conditions. One student was treated at the scene and released.

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The cause of the fire is under investigation, officials said.

Fox News' Stephen Sorace and the Associated Press contributed to this report.