A last-ditch effort by pro-gun groups to delay the Trump administration’s ban on bump stocks lingered at the U.S. Supreme Court on Tuesday, even as the government said the measure took effect.

While one request to stay the bump stock ban was rejected by Chief Justice John G. Roberts Jr., another awaited word from Justice Sonia M. Sotomayor. She asked for a response from the Justice Department, where in December officials announced that they were banning the devices, which are attached to rifles and essentially help speed up how quickly they can be fired. The devices gained notoriety after a gunman used them in the 2017 Las Vegas massacre.

The Justice Department filed its response late Tuesday afternoon. It was unclear when Sotomayor might act and what that could mean for the status of the ban. A Justice Department official said Tuesday that its understanding was that the ban had gone into effect as scheduled.

When the Justice Department announced late last year that it was banning bump stocks, the agency said weapons with the devices would be classified as machine guns because “such devices allow a shooter of a semiautomatic firearm to initiate a continuous firing cycle with a single pull of the trigger.”

Owners of the devices were told they had until Tuesday to destroy them or turn them over to authorities, creating a ticking clock for these legal challenges.

The devices became widely known after the October 2017 massacre at a country music festival on the Las Vegas Strip. A gunman firing from a nearby hotel killed 58 people and wounded hundreds more before killing himself. Authorities who searched his hotel room found more than a dozen weapons with bump stocks attached.

Several months later — after a February 2018 shooting rampage at a Parkland, Fla., high school that did not involve bump stocks but fueled a nationwide push for stricter gun laws — President Trump announced that he had signed an order directing the Justice Department to change regulations to ban the devices.

Gun rights groups and bump stock owners pledged to fight the move in court, with an attorney saying that the government was “actively attempting to make felons out of people” who had legally acquired and possessed them.

In court filings, groups challenging the change, along with their members, have said the bump stock ban “is the very embodiment of a violation of the separation of powers.” They also accused federal officials of overstepping their authority and twisting the facts. Justice Department officials have responded in court papers by saying that they had “corrected a confusing and erroneous agency interpretation” and that the change would improve public safety.

Gun Owners of America, one of the groups that filed the request before Sotomayor asking that the ban be delayed until they can appeal a lower-court ruling, argued that the case was about more than just bump stocks. The group wrote on its website that successfully blocking this change “will prevent a future anti-gun president from using these [regulations] to ban AR-15s and other semiautomatic firearms.”

In another case, Roberts on Tuesday morning denied a separate stay application also filed by gun rights groups and individuals. They had argued in court filings that allowing the change to take effect would force “hundreds of thousands of citizens . . . to surrender or destroy their property or face felony charges” for owning something previously approved of by the government.

The Firearms Policy Foundation, one of the groups filing the stay request to Roberts, said it was “disappointed” by the chief justice’s move but noted it plans to continue fighting the issue in court.

“The government’s strong-arm approach to changing criminal laws by executive fiat will continue to be strongly opposed,” the group said in a statement.

Sotomayor received one stay application because she is the justice who receives emergency cases from the U.S. Court of Appeals for the 6th Circuit, while Roberts received the other stay application because he takes cases from the U.S. Court of Appeals for the D.C. Circuit.

The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) told people who had bump stock devices that they had until Tuesday to “divest themselves of possession,” recommending they turn them over at an ATF office or destroy them. The bureau also posted a list of instructions for ways to destroy them, warning that using other methods “may be legally insufficient.” A spokeswoman for ATF declined to comment on the ban’s status Tuesday, referring questions to the Justice Department.

A federal judge ruled last month that the ban could go forward, saying it was “reasonable” for ATF to determine that the devices performed the same function as a machine gun and should be subject to the same restrictions.