NASHVILLE (AP) — Gov. Bill Haslam has signed a bill that requires cities and counties in Tennessee to buy metal detectors, hire security guards and check bags at many public buildings, parks and buses, or let handgun permit holders bring in their guns.

The Republican governor signed the legislation Friday. He has mentioned that a veto could be easily overridden.

Nashville and Knoxville officials have said the law offers bad choices and could be costly. The new law makes gun-rights groups eligible for triple attorney's fees in lawsuits if they believe local governments are wrongly banning guns.

Critics said the law could force Nashville to allow guns at its main bus station, and on buses that thousands of school children use.

The NRA says the law holds local governments responsible for keeping citizens safe.