DANVILLE -- Three 12th-grade girls were sickened -- one hospitalized as a precaution -- after apparently eating chocolate laced with marijuana, the San Ramon Valley Unified School District reported today.

The girls went to the school office of Del Amigo High School about noon showing signs of nausea, said district spokesman Terry Koehne. School staff called 911, and one of the girls was taken to the hospital. The other two girls were sent home.

Koehne said the girls said they had eaten a laced piece of chocolate -- likely a brownie -- before going to school today. They told school officials they had gotten the chocolate from a male student. It was unclear whether the girls knew that it contained marijuana.

School administrators are investigating the incident, including the suspected source of the drugs, Koehne said.

"There will be consequences," he said.