A chlorine spill Friday morning temporarily shut down Peekskill Middle School and sickened at least 19 students.

School officials say the chlorine spilled from a small tanker truck on campus at around 9 a.m. at the Ringgold Street school. The driver of the truck was bringing the chlorine to the school's pool, but was overcome by fumes. A cloud of the chemical seeped into the school, causing some students to feel ill.

Nineteen students and five staff members were taken to the Hudson Valley Hospital Center, while others were treated at the scene. All suffered from severe headaches and nausea, but are expected to be OK.

The other 700 students were evacuated to the high school before the decision to close the school for the day. Students and staff were later allowed back into the building to gather their belongings.

Nearly 50 gallons of chlorine seeped into storm drains, and HAZMAT crews are checking levels in the nearby river.

Parents are expected to receive a letter urging them to seek medical attention for their children if they begin to feel ill.

The district says that it plans to review its procedures to avoid similar incidents in the future.