SAN DIEGO (CBS 8) - A disturbing discovery at a Mission Bay park -- police say razor blades were found planted in the grass. And it's not the first time this has happened.
Officials say it's been a sporadic problem, the last reported incident was in April when two children were cut by razors in the same area.
"Anyone that was playing in that area could have gotten hurt and it's really sad. It's really sad," one parkgoer said.
Armed with rakes and metal detectors, parks and recreation employees searched Bonita Cove Park Saturday looking for more razors after a man called 911 around 11 a.m. to report seeing two sticking up in the grass area located right next to the children's playground.
"Well, I think it's very upsetting. Irritating," Jim Nugent said.
Jim Nugent was at the park with his 3-year-old grandson Curtis.
While he never saw the blades, his wife did saying it was obvious someone put them there on purpose.
"She said it looked as if someone made a slit in the lawn and upended a razorblade with the sharp corner protruding," he said.
Not wanting to take any chances, police roped off both the grass and playground.
In total, three razor blades were collected. You can see rust on them -- leading detectives to question how long they've been there.
"The blades are rusted...it gets watered daily so I don't know if it was leftover or if this is a new case," San Diego police Lt. Eric Hays said.
This is the fifth time razor blades have been planted at the park.
In 2013, officers came here on three different occasions. But the last time they were here was in April of this year, when nearly 20 razor blades were found in the exact same spot.
Two children -- a 7-year-old and 15-year-old -- were hurt in that case.
Fortunately, no one was hurt Saturday. Regardless, parents and kids are upset.
"I think it's a horrible thing to do to children, especially in the play area...you shouldn't do that," Maria McCombs said.
Police meanwhile, maintain they are actively working this case and are confident they'll make an arrest.
"We do share the same frustration as the people that attend the festivities. It takes some time...we have detectives working on it all the time," Lt. Hays said.
Police did interview people, specifically those with RVs who spent the night here to see if they saw anything suspicious.
One man said he thought he saw someone in the grass area but no details were offered beyond that.
Detectives will analyze the razor blades for potential DNA evidence.