Gov. Bruce Rauner will move to clamp down on rampant gun violence in Chicago Tuesday, when he signs legislation to punish people convicted of trafficking firearms into Illinois with prison sentences of up to 30 years.

There have been more than 400 homicides in Chicago in so far 2016, despite the city's strict gun policy that requires permits to screen for criminal records and other disqualifiers. Investigators say most of the firearms recovered at crime scenes in recent years were bought in other states.

Under the new law, a first conviction of trafficking guns will carry a sentence of four to 20 years in prison. A subsequent offense will be punishable by up to 30 years.

Catherine Kelly, a spokeswoman for Rauner, said the Republican governor will sign the bill in Chicago on Tuesday morning.

Prosecutors who lobbied for the bill say the long sentences are necessary to deter future offenders.

Nearly 60 percent of the firearms used in crimes in Chicago have been traced to other states, according to a 2014 report from the mayor's office, which blamed "weaker gun laws" in those places. About 20 percent came from Indiana, where no permit is required to buy firearms and private sellers don't have to conduct background checks.

The bill drew opposition from the American Civil Liberties Union in Illinois, which argued the sentences are too severe. The group said it supports the goal of removing illegal guns from the streets but is skeptical the new law will solve that problem.