Sony has said its PlayStation network is back online after services were shut down following a cyber-attack.
The company said an attempt had been made to "overwhelm our network with artificially high traffic" on Sunday.
Users' personal information was not breached, it added in a blog post.
The hackers claiming responsibility also tweeted claiming there was a bomb threat on a flight carrying Sony online president John Smedley.
Smedley confirmed his flight, bound for San Diego, had been diverted to Phoenix, Arizona for "security reasons".
Sony said the FBI was investigating the security incident.
Gamers were unable to access the PlayStation Store and online gameplay during the attack.
"The networks were taken offline due to a distributed denial of service attack," Sony said.
"We have seen no evidence of any intrusion to the network and no evidence of any unauthorised access to users’ personal information."
In light of the security breach, Sony has suspended planned maintenance on its network due to be completed on Monday.
PlayStation has previously been a target of attacks, with millions affected when the network was taken offline in 2011.