The FBI said Monday it successfully used a mysterious technique without Apple Inc.’s help to hack into the iPhone used by a gunman in a mass shooting in California, effectively ending a pitched court battle between the Obama administration and one of the world’s leading technology companies.

The government asked a federal judge to vacate a disputed order forcing Apple to help the FBI break into the iPhone, saying it was no longer necessary. The court filing in U.S. District Court for the Central District of California provided no details about how the FBI did it or who showed it how. Apple did not immediately comment on the development.

The brief court notice left important questions unanswered: Who showed the FBI how to break into iPhones? How did the government bypass the security features that Apple has invested millions of dollars to build into its flagship product? Are newer iPhones vulnerable to the same hacking technique? Will the FBI share its information with scores of state and local police agencies that said they also need to break into the iPhones of criminal suspects? Will the FBI reveal to Apple how it broke its security? Did the FBI find anything useful on the iPhone?

The surprise development also punctured the temporary perception that Apple’s security might have been good enough to keep consumers’ personal information safe even from the U.S. government — with the tremendous resources it can expend when it wants to uncover something.

The FBI used the technique to access data on an iPhone used by gunman Syed Farook, who died with his wife in a gun battle with police after they killed 14 people in San Bernardino, Calif., in December.

U.S. magistrate Sheri Pym of California last month ordered Apple to provide the FBI with software to help it hack into Farook’s work-issued iPhone. The order touched off a debate pitting digital privacy rights against national security concerns.

Apple was headed for a courtroom showdown with the government last week, until federal prosecutors abruptly asked for a postponement so they could test a potential solution that was brought to them by an unidentified party the previous weekend. Technical experts had said there might be a few ways an outsider could gain access to the phone, although the FBI had insisted repeatedly until then that only Apple had the ability to override the iPhone’s security.

The case drew international attention and highlighted a growing friction between governments and the tech industry. Apple and other tech companies have said they feel increasing need to protect their customers’ data from hackers and unfriendly intruders, while police and other government authorities have warned that encryption and other data-protection measures are making it more difficult for investigators to track criminals and dangerous extremists.

The withdrawal of court process also takes away Apple’s ability to legally request details on the method the FBI used. Apple attorneys said last week that they hoped the government would share that information with them if it proved successful.

The encrypted phone was protected by a passcode that included security protocols: a time delay and self-destruct feature that erased the phone’s data after 10 tries. The two features made it impossible for the government to repeatedly and continuously test passcodes in what’s known as a brute-force attack.