gunman opened fire at an elementary school in Carlsbad, California,

gunman opened fire at an elementary school in Carlsbad, California, injuring two students who were outside during lunch Friday, police said.

The students, ages 6 and 7, were shot and suffered minor injuries, said Lt. Jay Eppel of the Carlsbad Police Department. Both were flown to Rady Children's Hospital in San Diego.

Construction workers at Kelly Elementary School detained a 41-year-old male suspect shortly after noon until officers arrived, Eppel said. Police do not suspect the man has a relationship with any students at the school.

Worker Carlos Partida told CNN affiliate KGTV that he got into his truck and was able to knock the gunman down with the vehicle. The man, dressed in black, was then tackled by other construction workers and witnesses.

The suspect's vehicle was parked near the school. Officers found a handgun and propane tank inside, police said. The bomb squad was called to the scene to conduct a more thorough search, Eppel said.

Students were taken to a local park to be picked up by their parents.

Pete Anderson, who operates a small research vineyard near the school, said he was tending vines when "I heard something like a gunshot, followed by another."