Human remains were discovered crammed inside a suitcase that was floating in a lake in Northern California on Tuesday.

Volunteers cleaning Lake Merritt spotted the suitcase adrift around 11 a.m. near the 1900 block of Lakeshore Avenue and found the body of what appeared to be a man in his 30s "kind of like in a fetal position," Kevin Shomo, one of the volunteers with Lake Merritt Institute, told FOX2 KTVU.

"We grabbed one end [of the suitcase] and we realized it was too heavy. So, we pulled it close enough to us and we said, 'Oh wow, this thing is heavy,' so we unzipped it and that's what we found," Shomo said.

It was unclear how long the body had been in the suitcase or water. Police were investigating where the suitcase first entered the water.

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suitcase floating in Lake Merritt

Volunteers cleaning Lake Merritt in Oakland, California, discovered the suitcase on Tuesday. (FOX2 KTVU)

"Part of the investigation is trying to determine where the body could have floated from," Oakland police Capt. Alan Yu told the station. "It could be any part of the lake, and we're looking at all those possible outcomes."

authorities fishing out suitcase

After finding a body inside, the volunteers called police. (FOX2 KTVU)

Police said the body appeared to have several visible injuries, without elaborating, East Bay Times reported.

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Witnesses and residents say the gruesome Halloween discovery near the popular wildlife refuge and jogging location was shocking.

police investigating scene on Lake Merritt

It was unclear how long the body was inside the suitcase or in the water. (FOX2 KTVU)

"Oakland definitely has its crime, but to see something this gruesome is quite shocking," resident Shana O’Shae, 45, told the newspaper. "It’s insanity."

police car parked next to Lake Merritt

Police are investigating where the suitcase may have first entered the water. (FOX2 KTVU)

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Authorities asked anyone with information about the body or surveillance video showing suspicious activity regarding the incident to contact the department.