The Indianapolis City-County Council passed a proposed gun control measure by a vote of 18 to five Monday evening.

Introduced by Mayor Joe Hogsett as part of his public safety plan, Proposal 156 was initially approved nine to four by the city's Public Safety and Criminal Justice Committee. 

The ordinance increases the age required to purchase a gun in the city to 21 years old, bans "assault rifles" within city limits and mandates a license to carry.

"Tonight's Council votes on Proposals 149 and 156 prove that Indianapolis and its leadership won't back down from taking bold steps to protect residents and neighborhoods," Hogsett said in a statement. "I applaud the Council's bipartisan support for funding our partnership with U.S. Attorney Zach Myers, holding the worst of the worst offenders to account." 

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Firearms on the wall at a store

The Indianapolis City-County Council on Monday passed a proposed gun control measure by a vote of 18 to five. (AP Photo/Andrew Selsky, File)

"I also wish to thank those who approved our common-sense gun safety measures, including a ban on semiautomatic assault weapons, increasing the purchasing age to 21, requiring handgun licenses, and removing the concealed carry of firearms," the mayor continued. "Tonight we are sending a clear message of where we stand about the causes of gun violence and the proliferation of illegal weapons on our streets."

The plan, however, is not immediately enforceable, as state law prohibits local governments from enforcing this kind of gun regulation. The city would be allowed to enact the measure if state regulations are lifted or the law is changed by the legislature or the courts, according to WTHR.

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Proposal 156 was introduced by Mayor Joe Hogsett as part of his public safety plan.

Proposal 156 was introduced by Mayor Joe Hogsett as part of his public safety plan. (Getty)

Opponents of the plan argue that it is unconstitutional.

"I'm voting against this because I disagree with the toothless language and the policy itself, but also because it plainly violates state statute and state constitution," Republican Council minority leader Brian Mowery said, according to WTHR.

Meanwhile, supporters of the proposal describe it as a necessary public safety measure.

A photo of Colt M4 Carbine and AR-15 style rifles

The ordinance increases the age required to purchase a gun in the city to 21 years old, bans "assault rifles" within city limits and mandates a license to carry. (PATRICK T. FALLON/AFP via Getty Images)

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"You may call this toothless, but this is us taking a stand because it's too much," Democrat Councilor Ali Brown said.

The council also approved a proposal for the city to add three federal prosecutors who will focus on prosecuting federal gun crimes as part of the mayor's public safety plan.