The FBI and Department of Homeland Security are investigating a cyberattack against the city of Torrance which knocked offline City Hall’s email system and the city’s ability to process credit card payments, municipal spokesman Michael Smith said Friday.

The attack occurred Sunday. It also eliminated the city’s ability to update its own website.

It’s unknown how long the crippled municipal website, email, and credit card payment system will remain inaccessible, Smith said. “We don’t have a timeline at this point,” he said, adding that fire and police services are unaffected and continue to function.

Residents may still provide credit card information to make payments which will be processed later, Smith said.

No residents’ personal information was compromised in the attack, he added.

For those needing to send an email, the city has listed alternate addresses at gmail.com for many municipal officials and departments at torranceca.wordpress.com.

Mayor Pat Furey did not respond to a request for comment sent Friday to his new gmail address.

Councilman Mike Griffiths, now retired but once an owner of a high-tech company, said he hadn’t received any updates from the city since the initial news broke earlier in the week. But he also said that isn’t surprising given the inherently sensitive nature of dealing with a cyberattack.

“It’s big and very complicated and serious,” he said. “The virus could have been planted a long time ago.”

“It does require extensive expertise,” he added, “to make sure we’re not wasting our time figuring out how to restore it.”

Cyberattacks are reportedly increasing on local governments around the country, website Govtech.com reported in December. It cited Emsisoft, a New Zealand-based cybersecurity company, as saying attacks against school districts, local governments and medical networks have reached “unprecedented” numbers.

“There’s undoubtedly a higher number of attacks this year,” the website quoted Emsisoft spokesman Brett Callow as saying. “This is the year that under investment in IT departments and software security has finally caught up with local governments.”

Emsisoft observed on its company blog hackers in May knocked the email and phone systems offline and disabled utility payment services in the Florida community of Riviera Beach after a police department employee opened an infected email attachment. Officials paid $600,000 to the hackers to get rid of the ransomware.

The same thing occurred Lake City, Florida, the next month. That time hackers collected $460,000.

And, in August, 22 Texas cities were attacked simultaneously, govtech.com reported.

“Typically, a ransomware attack occurs when someone opens an email attachment that’s infected with malware,” the website said. “Opening the link allows the virus to encrypt files, emails and documents that can only be unlocked with a code.

“Hackers then demand a large sum of money in exchange for the code,” it added.

In 2016, hackers demanded $8,500 to unfreeze 88 servers belonging to the Orange County Transportation Authority. The agency refused to pay and it eventually cost about $660,000 to fix them.

Smith, the Torrance spokesman, did not say whether the city had received a ransomware demand from hackers.