Fourteen blades commonly used in X-Acto knives were found buried in the sand of a private Newport Beach playground, prompting increased patrols and inspections at all 27 city-owned parks, officials said Monday.

The blades turned up after a 5-year-old cut his foot Saturday while playing in the park in a gated community. The child was not seriously injured.

The discovery awakened memories of a series of similar discoveries in south Orange County when razor blades, nails and glass shards were found near slides and other playground equipment in 2002. A Mission Viejo woman is in prison in connection with those incidents.

"We're looking into whether this is done intentionally or accidentally," said Sgt. Bill Hartford, spokesman for Newport Beach police.