The reports, of a man seen in a residential area near Fairlands Drive and Pimlico Drive around 9:38 Wednesday morning, brought police on the run.
Pleasanton police Lt. Brian Laurence said police were on the scene in "one to two minutes."
"In light of recent tragic occurrences nationwide, we take these calls very seriously," Laurence said.
When the same person was spotted by a Zone 7 employee running into the Arroyo Del Valle, just north of Stoneridge Drive, east of Santa Rita Road, police quickly established a perimeter. They also called in the East County Tactical Team, the SWAT team made up of Pleasanton and Livermore police, which happened to be training nearby in Livermore.
The team brought in an armored vehicle to approach along the service road.
Police apprehended the suspect, who turned out to be a 16-year-old boy with an air gun.
"He went down in the arroyo and soon after we were able to observe hm and he stayed put. The SWAT team members were able to approach him and give him commands, and he was very cooperative to the questions," Laurence said. "To have the East County Tactival Team was helpful, too. They were on the scene in about 10 minutes as well."
Although it was a false alarm, Laurence credited residents for their vigilance.
The teen was cited for discharging an air gun inside city limits and released to a parent. No one was injured.
As a precaution, the staff and children at the nearby Hacienda Preschool were instructed to shelter in place during the incident.
Pleasanton Police Department reminded residents that shooting air guns is illegal in the city.
Laurence said people with Airsoft weapons should be careful.
"It's fortunate with these type of incidents, especially with how realistic these weapons look, that we were able to avoid a tragedy," he said.