A St. Paul city employee is on leave after he used heavy equipment to tear down what was thought to be an abandoned tent outside Arlington Hills Recreation Center on Wednesday, seriously injuring the woman inside.

Emergency responders rushed the 49-year-old woman to Regions Hospital, where she remains in stable condition, police said.

“At a time when people experiencing homelessness are particularly vulnerable, this tragedy is devastating,” Mayor Melvin Carter said in a statement. “I have reached out to express my remorse to the individual involved and to arrange for the city to cover medical bills that arise as a result of this incident, and I am working with my team to determine how this horrible accident occurred.”

The Parks and Recreation worker was instructed to remove the debris from outside the rec center at 1200 Payne Avenue on Wednesday afternoon, but police say he failed to double check that it wasn’t occupied.

The worker used a four-wheel Bobcat utility vehicle to break down the tent — as is common practice in the maintenance of park sites and cleaning of abandoned structures, a city spokesman said.

Sometime during the removal process, the employee realized someone was injured inside and called 911.

The incident remains under investigation and the worker has been placed on standard leave. “The city is working to determine what led to the effort to clean the area, and how it was not known that the tent was occupied,” said St. Paul spokesman Peter Leggett.

The city employee of two years holds a commercial driver’s license to operate that machinery.