For the first time since a bill to overhaul Massachusetts firearms laws was introduced in June, a group that represents nearly 400 police chiefs publicly spoke out against the bill.

House Democrats Tuesday held a well-attended hearing on their bill in the Gardner Auditorium, the State House’s largest hearing room, which drew dozens of supporters as well as critics, including Mark Leahy, retired police chief in Northborough and executive director of the Massachusetts Chiefs of Police Association, the Boston Globe reports.

“Our strict Massachusetts gun laws work,” Leahy said. “The registration of firearms will not reduce gun violence.”

Leahy said the chiefs’ concerns with the bill include a provision that limits where gun owners may bring their weapons. He pointed out that the bill languagedoesn’t carve out off-duty police officers and state troopers and argued that “criminals will not be deterred by these measures.”