OCEAN CITY, Md. (AP) — Officials warned people to stay out of the ocean at several beaches in Maryland, Delaware and Virginia after they said medical waste, including hypodermic needles, washed ashore. The source of the waste was under investigation.

Officials banned swimming, wading and surfing at Assateague State Park Sunday morning after Maryland Park Service rangers found several needles and needle caps, feminine hygiene products and cigar tips along the beach, Maryland Department of Natural Resources spokesperson Gregg Bortz said in an email.

A few more needles were found Monday and the ban on swimming in the ocean continued at the park, he said.

There have been no reports of injuries or people encountering these items while swimming, Bortz said. The department was working with other local, state, and federal agencies to determine when it’s safe for people to enter the water.

All of Assateague Island National Seashore’s ocean-facing beaches in Maryland and Virginia were closed to swimming and wading.

Maryland’s Department of Emergency Management raised its state activation level to “partial” in support of the incident.

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In Ocean City, Maryland, the beach patrol temporarily banned swimming Sunday after discovering medical waste on town beaches. Emergency Services Director Joe Theobald stressed in a statement that the situation was serious and said town officials were working with the Worcester County Health Department to investigate the source.

“Until we are confident that the situation is under control, we recommend wearing shoes on the beach and avoiding the ocean entirely,” he said.

On Monday afternoon, Theobald said the amount of debris had “significantly decreased.” The town was continuing to monitor the situation, particularly as the next high tide cycles approached Monday evening and Tuesday morning.

Delaware’s Department of Natural Resources and Environmental Control advised beachgoers to leave the beaches from the Indian River inlet to Fenwick Island Sunday afternoon and to refrain from swimming after reports of waste washing ashore on nearby Maryland beaches, the agency said in a statement. The department confirmed only minimal waste on Delaware beaches, including plastic caps and a single needle found near Dewey Beach.

“Despite the low level of waste observed, DNREC is taking the situation seriously and advising caution,” the agency said in a statement. The department maintains Delaware’s two state park beaches, but decisions about municipal beaches are up to town officials.

Delaware’s Dewey Beach temporarily barred swimming in the ocean Sunday. In an update Monday, the town said it was continuing to address the issue. Fenwick Island officials closed the beach for swimming Sunday and said in a statement that beaches would be inspected again late Monday and on Tuesday morning before a decision would be made on reopening.