Universal’s Volcano Bay Water Theme Park in Orlando was closed for a time early Sunday after some guests and workers experienced electrical shock symptoms, with four lifeguards being transported to hospitals.

News sources say people reported feeling tingling in their legs and buzzing in their ears while they were walking around the park. Patrons who were in the water at the time were ordered to get out immediately

Universal paramedics reportedly treated at least one person for symptoms that included a rapid heart rate. The workers who were sent to local hospitals were released later.

Universal blamed the problem on “technical issues.” In a statement, the company said that as specific areas of concern were identified, the rides in those areas were closed. Eventually, the entire park was closed “out of an abundance of caution.”

The company said it worked with the Orlando Utilities Commission (OUC), outside electrical contractors and its own experts to test and repair the park’s electrical system.

According to the OUC, the problem was with underground electrical cables.

OSHA is investigating the incident.