NASHVILLE (AP) — Metro Nashville fought a losing battle this spring as a state law passed that lets people with gun permits enter city buses and its main bus terminal with their guns. Nashville is now among several cities in Tennessee to tweak its bus system rules just enough to follow the new law without advertising that guns can be carried more freely.

To comply with the law, which took effect July 1, Nashville changed its transit system's code of conduct, which had banned all weapons, to banning only those that are "unauthorized." No mention is made of the new law.

But the change in Nashville's rules doesn't provide much comfort to some parents whose children are among the thousands who use the city bus system to get to school every day.

"There's not going to be any way of knowing whether or not someone's gun is 'authorized' or 'unauthorized,'" said Beth Joslin Roth, a gun-control advocate whose son takes Nashville buses to school and who heads the Safe Tennessee Project.

The law, which was strongly supported by the National Rifle Association, gives cities and counties a choice: either they must use metal detectors, hire security guards and check people's bags at many local facilities; or they must let handgun permit-holders bring in their guns.

Between 4,500 and 5,600 students use Nashville's free city bus pass program. All public high schoolers and some students in grades 5 through 8 qualify, and the downtown station teems with students when school is in session, as police and security guards watch guard.

Signs at Nashville's Music City Central bus terminal still say "no weapons" more than a week after the law took effect, but Metropolitan Transit Authority officials said they're in the process of revising them.

In Chattanooga, the new transit policy says, "Weapons are prohibited except as permitted in accordance with T.C.A. 39-17-1351," without explaining that the law being referenced lets permit-holders carry guns.

Lisa Maragnano, Chattanooga Area Regional Transportation Authority executive director, hardly endorsed the law.

"We will comply with the law, we won't encourage it," she said in an email.

Signs at Knoxville's downtown station and on buses were similarly worded, said the mayor's spokesman, Jesse Mayshark.

Memphis officials have also said their buses and stations now allow permit holders to carry guns.

Transit officials have said it's logistically impossible to add metal detectors at stations and secure all city buses. Even trying to apply airport-style security to a public transit system would cost millions and create commuter chaos.

Nashville Metropolitan Transit Authority spokeswoman Amanda Clelland said that, under the new policy, officials can remove someone from transit property who is carrying a gun without a permit.

Roth said her son, then a middle schooler, was on a city bus pulling into Music City Central last spring when four teenagers were wounded in a shooting. The bus driver immediately drove away from the station, she said.

Gun rights and gun control groups have mentioned the same crime to argue opposite perspectives about who should be allowed guns at the station and on buses.

Rep. William Lamberth, the Cottontown Republican who sponsored the bill, said the shooting revealed that security at the station was insufficient. Under his law's choices, he said, either metal detectors would assure people aren't getting guns into the station, or people with permits would have guns to protect themselves in case of a shooting.

The law also gives groups like the NRA standing to sue for triple attorney's fees if they believe a local government wrongly barred someone from carrying guns.

Critics have also said the law could conflict with existing state law, which makes it a felony to bring guns into a facility used for school purposes, including Nashville's bus station.