Hackers used Amazon.com’s cloud computing service to launch an attack on Sony PlayStation in April, forcing Sony to shut down the popular gaming network after personal accounts for more 100 million customers were compromised.

Hackers launched the attack from Amazon Web Service’s EC2 service, according to a report by Bloomberg. The report said the hackers used an alias to rent a server through Amazon’s cloud service. Bloomberg said that the account has been shut down and the FBI is likely to seek information from Amazon about the attack. Amazon declined to comment.

The hack attack raises more concerns about the security of cloud-computing services such as Amazon’s. Last month, Amazon’s cloud service suffered a failure that downed numerous websites relying on the web services. Amazon said the failure was not due to hackers.

In mid April, Sony’s PlayStation Network and Qriocity, its media streaming service, were shut down after a hacker attack. The Japanese company later admitted that its Sony Online Entertainment (SOE) division, previously thought to be untouched by the hack that shuttered its PlayStation Network, had also been compromised.

Sony has said that the attack was carried out by sophisticated criminals who carefully planned the attack.