(CNN) Sections of Venice Beach in Los Angeles were blocked off Sunday after authorities discovered needles and other medical supplies had washed up on shore.

Lifeguards found a "large amount" of medical supplies around 11:30 a.m. PST along the beach south of the Venice Beach Pier, according to tweets from the Lifeguard Division of the LA Fire Department.

At Approx. 11:30 AM today @lacolifeguards visualized a large amount of medical supplies along the shoreline South of the #VeniceBeach Pier. The the area has been cordoned off and notifications to @lapublichealth @LAPDHQ @USCG @lacdbh @LACOFD pic.twitter.com/YtzpJZf8Iw — LACoFD Lifeguards (@LACoLifeguards) November 10, 2019

Authorities said on Twitter they did not know where the medical supplies and needles came from. Lifeguards continued to search the beach and will monitor the area "for the safety of public use until the investigation and cleanup are complete," the LA Fire Department said.

#DriftIC This area will continue to be monitored for the safety of public use until the investigation and cleanup are complete. pic.twitter.com/0RYU5b4Z7l — LACoFD Lifeguards (@LACoLifeguards) November 10, 2019

Lifeguards said they also alerted other agencies, including the LA County Department of Public Health, US Coast Guard and police.

Venice Beach, west of Los Angeles and just south of Santa Monica, is known for its canals, trendy shops and colorful boardwalk.