An unexplained surge of traffic to Vineyard Gazette websites Tuesday caused to go down briefly just after noon and remain slow for several hours.

Acquia, the company that hosts the Gazette’s websites, said the cause appeared to be a distributed denial-of-service attack from computer addresses in Russia and Ukraine. A distributed attack is one in which a site is accessed at the same time by multiple computers, usually bots, with different IP addresses.

“I would say that it is possible this is legitimate traffic, but given the countries of origin of the majority of your traffic (Russia,Ukraine) along with the nature of your content (newspaper local to Martha’s Vineyard), I think that is unlikely,” a representative of the hosting service told the Gazette in an online communication.

Jane Seagrave, publisher of the Gazette, said there was no obvious reason for the newspaper to have been targeted this week, and no immediate evidence that other media sites were affected. “While almost five per cent of our traffic comes from outside the United States, typically Russia and Ukraine is a tiny fraction of that,” she said.

Gazette webmaster Graham Smith worked with Acquia and OHO, a Boston-based web services company that consults to the Gazette, to stabilize the site, which was operating normally by late afternoon. Ms. Seagrave said the newspaper has temporarily blocked all traffic from Russia and Ukraine.