A partial failure at Amazon Web Services' (AWS) cloud-computing infrastructure today paralysing popular web sites such as Foursquare, Quora and Reddit.

Quora is a question and answer website and Reddit a news aggregator while Foursquare is a location-based social network.

The outage hit the Elastic Compute Cloud (EC2) service at Amazon's Viriginia site handling the AWS operations for the US East Coast. The problems started 1:41 am PT, according to Amazon's AWS status dashboard. Delays and errors were reported when connecting to servers over a network.

A long list of customers, mostly start-ups, depend on Amazon EC2, which offers servers on a pay-as-you-go basis, allowing customers scale up or down to suit their computing needs.

According to Amazon, it was making progress on addressing the problems but as of 5 am PT the troubles were continuing.

"We'll be back shortly, we hope. Sorry, it sucks for us too," a note on the web site of Quora said. The site allows people to ask and answer questions.