A US city has said hackers brought down their computer systems earlier this week and have demanded a ransom, which is reportedly $1m (£750,000).

Kaycee Lagarde, a spokesperson for Pensacola in Florida, said ransomware - which locks users out of their data until they pay money to restore access – was behind the cyber attack.

She would not say whether any personal or financial data was breached and said the city would notify residents and customers as warranted.

Information technology technicians have been working to restore services as officials determine what damage was done and what information might have been compromised.

The cyber security blog BleepingComputer claimed a group behind a ransomware strain known as Maze have claimed responsibility for the attack and demanded $1m from the city, which has around 52,000 residents.

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In emails exchanged with the website, the Maze hackers claimed they had stolen documents from the city.

They did not say whether they had given Pensacola officials a deadline or if they had threatened to release the documents if they did not receive the money.

Lawrence Abrams, the editor of BleepingComputer, said the Maze operators had authenticated their identity with proof of a different hack and by posting snippets of email exchanges with his blog on a dark-web payment site.

Pensacola officials declined to discuss who might have been responsible or any ransom amount demanded.

The city said it has restored some services, including email, phone services and utility online bill payments.

There have been a string of ransomware infections this year, with security researchers citing concerns ransomware could also disrupt next year’s US presidential election.

According to a recent report by the cyber security firm Emsisoft, almost a thousand US government agencies, educational institutions and health care providers were hit in an unprecedented barrage at a potential cost of more than $7.5bn ($5.6bn).

New Jersey‘s largest hospital system and the city of New Orleans are among the most recent US ransomware victims.

In May, a cyber attack hobbled Baltimore’s computer network and cost the city more than $18m (£13.5m) to repair.

During the summer, two Florida cities – Riviera Beach and Lake City – paid hackers more than $1m combined after being targeted.

Local officials in Pensacola, Florida, have not yet decided whether to pay the money. ​

The cyber attack took place less than a day after a Saudi aviation student killed three US sailors and wounded eight other people at a naval air station in Pensacola.

The FBI has said the attacks were not connected.