Detective Trevor Hall said the theft occurred between 3 p.m. Monday and 5 a.m. Tuesday.
Lynwood Elementary School Principal Ivy Morritt said the thieves cut a chain to unlock a gate and likely drove onto school property and up to the computer lab.
A custodian noticed the computers were gone when he checked classrooms Tuesday, Morritt said. Some old video cameras also were missing, she said.
The computers, in use since last fall at the K-5 school, are worth about $20,000, Morritt said. There were 30 in the computer lab and there are about 100 more at the school, she said.
School officials are hoping insurance will cover the cost of replacing the computers, Morritt said. School begins Aug. 20.
Police are asking for the public's help in solving the case. Bay Area Crime Stoppers is offering a reward of up to $2,000 for information leading to the arrest and prosecution of the suspects, police said.
Anyone with information on the crime is asked to call (800) 222-TIPS or Novato police at (800) 848-0101.