A landscaper was killed Tuesday after he fell into a cesspool at a Deer Park home.

Police said 34-year-old landscaper Sergio Reyes, of Central Islip, was riding a stand-up lawnmower at a home on Commack Road when the cesspool collapsed underneath him just before noon.

Reyes was found inside the 6-foot cesspool by a coworker and taken to Good Samaritan Hospital, where he was declared dead. Police said officers from the 1st Precinct helped pull Reyes out of the cesspool, where he was pinned against the side and trapped underneath the lawnmower.

Suffolk police said the federal Occupational Safety and Health Administration will investigate the workplace death, which appears to be a "tragic accident." Reyes worked for PM Landscaping, a family-owned business.

Police said it is not clear if Reyes died from drowning or from the lawnmower's weight. An autopsy is scheduled to determine a cause of death.

Reyes leaves behind his wife and daughter.

The Associated Press contributed to this report.