The Federal Bureau of Investigation has not been able to break the encryption on the phone owned by a gunman who killed 26 people in a Texas church on Sunday.

"We are unable to get into that phone," FBI Special Agent Christopher Combs said in a press conference yesterday (see video).

Combs declined to say what kind of phone was used by gunman Devin Kelley, who killed himself after the mass shooting. "I'm not going to describe what phone it is because I don't want to tell every bad guy out there what phone to buy, to harass our efforts on trying to find justice here," Combs said.

FBI official, citing encryption tech, says federal agents have not been able to access the Texas shooter's phone https://t.co/CacbcOGFxq — NBC News (@NBCNews) November 7, 2017

The phone is an iPhone, The Washington Post reported today:

After the FBI said it was dealing with a phone it couldn’t open, Apple reached out to the bureau to learn if the phone was an iPhone and if the FBI was seeking assistance. Late Tuesday an FBI official responded, saying it was an iPhone but the agency was not asking anything of the company at this point. That’s because experts at the FBI’s lab in Quantico, Va., are trying to determine if there are other methods to access the phone’s data, such as through cloud storage backups or linked laptops, these people said.

Encryption fight between phone makers and government

The US government has been calling on phone makers to weaken their devices' security, but companies have refused to do so. Last year, Apple refused to help the government unlock and decrypt the San Bernardino gunman's iPhone, but the FBI ended up paying hackers for a vulnerability that it used to access data on the device.

Deliberately weakening the security of consumer devices would help criminals target innocent people who rely on encryption to ensure their digital safety, Apple and others have said.

"With the advance of the technology in the phones and the encryptions, law enforcement, whether it's at the state, local, or the federal level, is increasingly not able to get into these phones," Combs said yesterday.

Combs said he has no idea how long it will take before the FBI can break the encryption. "I can assure you we are working very hard to get into the phone, and that will continue until we find an answer," he said. The FBI is also examining "other digital media" related to the gunman, he said.

There are currently "thousands of seized devices sit[ting] in storage, impervious to search warrants," Deputy Attorney General Rod Rosenstein said last month.