LAS VEGAS — A freeway-side billboard for a Las Vegas gun range was vandalized late Wednesday or before dawn Thursday to change an advertisement inviting tourists to fire an assault-style rifle to say, “Shoot A School Kid Only $29.”

The message, which had said “Shoot a .50 caliber only $29,” was taken down within hours and police were investigating. Officer Larry Hadfield said authorities were called a little before 5:30 a.m. Thursday.

A local guerrilla art collective called INDECLINE took credit for the act with a statement to KTNV-TV in Las Vegas calling for reforming gun laws “that are currently placing value on assault weapons over that of human life.”

An email to INDECLINE by the Associated Press was not immediately answered.

A worker at Battlefield Las Vegas, the gun range that invites tourists to shoot a .50-caliber semi-automatic rifle, referred questions to managers who did not immediately respond to telephone and email messages.

The billboard near Interstate 15 is about 3.5 miles (5.6 kilometers) from the Mandalay Bay resort, where a gunman firing assault-style rifles from 32nd-floor windows killed 58 people and injured more than 800 late Oct. 1 in the deadliest mass shooting in modern US history.