BEIRUT — Islamic State fighters on Tuesday launched a surprise attack on a Syrian border town recently seized by U.S.-backed Kurdish forces, taking positions in the eastern part of the town and waging fierce gun battles with its defenders, activists said.

The attack on Tal Abyad resembled another surprise assault by the IS group last week on the border town of Kobani, where Kurdish forces backed by U.S.-led airstrikes had driven out the extremists in January. The two attacks brutally displayed the extremists’ resilience and signaled a possible change in tactics following a string of defeats at the hands of Kurdish forces.

Rami Abdurrahman, head of the Syrian Observatory of Human Rights, a U.K.-based monitoring group with a network of activists inside Syria, said 223 civilians were killed in Kobani, including “scores” of women and children, as well as 37 Kurdish fighters.

Kurdish fighters captured Tal Abyad two weeks ago – denying the IS group a crucial border crossing used to bring in supplies and foreign fighters and causing immediate price hikes in areas under IS control. Backed by U.S.-led airstrikes, the Kurds then advanced south toward the extremist group’s de facto capital, Raqqa.

In the remote northeastern city of Hassakeh, meanwhile, Syrian government forces and allied paramilitary National Defense Forces retook Eastern Ghoweiran, a neighborhood seized by IS militants last week, activists and Syrian state television said Tuesday.

Fighting has raged in Hassakeh since the IS group attacked several southern neighborhoods held by government troops earlier this month. The violence has left dozens killed and forced at least 60,000 residents to flee, according to activists and a Western aid group.

Turkey-based opposition figure Mustafa Osso said IS captured three predominantly Arab neighborhoods in Hassakeh last week and that fighting was continuing in the city.

The U.S. military said Tuesday that the U.S.-led coalition has conducted seven overnight airstrikes near Hassakeh,