KYIV, Ukraine (AP) — Ukraine rushed reinforcements to its northeastern Kharkiv region on Friday to hold off a Russian attempt to breach local defenses, authorities said, signaling a tactical switch in the war by Moscow that Ukrainian officials had been expecting for weeks.

Kharkiv’s regional governor, Oleh Syniehubov, said intense overnight shelling targeted Vovchansk, a city with a prewar population of about 20,000 that is less than 5 kilometers (3 miles) from the Russian border. The barrage, which used powerful guided aerial bombs, artillery, rockets, tanks and mortars, killed at least one civilian and wounded five others, prompting authorities to begin evacuating about 3,000 people.

Then, around dawn, Russian infantry tried to penetrate Ukrainian defenses near Vovchansk, the Ukrainian Defense Ministry said, adding that it had deployed reserve units to fend off the attack.