The European Union Naval Force says Somali pirates have boarded an oil tanker off East Africa and a Russian warship is rushing to intervene.

Cmdr. John Harbour says it is unclear whether the pirates are fully in control of the Liberian-flagged ship, which is named the Moscow University. The 106,000 ton ship has 23 Russian crew onboard.

Tuesday's dawn attack occurred about 500 miles (800 kilometers) east of the Somali coast.