"Please don’t take the signs," Marine Safety Captain Larry Giles with the Encinitas Lifeguard Department implored at a press conference Sunday morning while giving an update on Saturday’s shark attack at Beacon’s Beach.

"You’re stealing public property," he added, after people had stolen from the beach north of San Diego at least 20 to 30 signs warning swimmers to stay out of the water while authorities investigate for sharks. Giles said the department was forced to order $800 in new signs.

A 13-year-old boy sustained ear and shoulder injuries in Saturday's early-morning attack. He was taken to the hospital in critical condition but was upgraded Sunday to serious condition.

"We want to have those signs on hand if we have to re-establish those signs in the future," Giles said while pleading to the public to leave the signs alone.

But the public apparently didn't listen. A lifeguard reopening a portion of the Encinitas Beach Monday morning found that there were no signs left. Encinitas lifeguards had placed upwards of 70 warning signs at beaches from Carlsbad to Encinitas on Saturday.

Presumably, they were all stolen, Giles told NBC 7 while assisting his team in reopening the shoreline.

The signs cost several dollars each, according to Giles.

Giles said his team has followed up with the San Diego Sherriff’s Department after witnesses reported the license plates of some of the alleged thieves.