By Rachel Leigh| February 9, 2012 at 8:42 PM EST - Updated June 26 at 2:18 PM
GREENACRES, FL (WFLX) — A middle school in Greenacres was placed on lockdown Thursday after an 'unknown chemical' was discovered.
According to officials at the Palm Beach County School District, two Tradewinds Middle School students dropped a plastic bottle with an unidentified chemical in the boys restroom in the gymnasium.
Children were taken out of the building and onto a field behind the school just before 9 a.m.
Palm Beach County School District spokesperson Nat Harrington said the incident was a prank involving four students and some chemical in the boy's bathroom near the gym.
According to the Palm Beach Post, the four students are in custody.
"Apparently there were four students totally involved. Two students allegedly gave the substance to two other students on a bus and gave them sort of instructions," said Harrington. "There was some discussion about how to handle it, the other two students who received this bottle then went into the bathroom dropped it and ran."
Harrington said two of the male students face felony charges.
The boys were transported to the Juvenile Assessment Center by school police. The boys have been suspended and are being processed for expulsion.