A cloud computing service managed by Amazon that crashed Wednesday also brought down an Energy Department site aimed at sharing clean technology practices with the private sector.
A note on the openei.com site Thursday afternoon said it was "temporarily down" and that engineers were "working aggressively to restore service."
Amazon's EC2 cloud in Northern Virginia also hosts a number of other federal websites, including recovery.gov, which tracks money spent on President Obama's stimulus plan, and several sites within the Treasury Department.
Other federal sites that use the Amazon cloud appeared to be functioning normally Thursday afternoon.
Amazon engineers still hadn't located the source of the crash by midday Thursday and the outage was causing trouble for several high traffic websites that used the Amazon service, including reddit.com, a popular site for ranking other web content, which was operating in an "emergency read-only mode."