Chinese Web surfers may be hanging dry after a deep-sea Internet cable was severed. Officials say they don't know what caused the break, which occurred off the coast of the Japanese city of Yokohama, Reuters reports. Repairs may take up to three weeks.

The severed cable linked Shanghai to the U.S. west coast, and caused reduced access speeds all the way to Hong Kong and Singapore. Many Web surfers are still able to access some domestic sites, but many overseas sites are unavailable.