After police recover some territory from Hong Kong’s protesters early Tuesday, demonstrators block a tunnel outside the government offices later that night.

HONG KONG—Protesters’ standoff with police intensified late Tuesday near government buildings after police reclaimed some territory for the first time in the 2 ½-week occupation.

The police’s tack to reassert control by removing barricades led to the reopening of Queensway, a main artery into the city’s business district that had been blocked since Sept. 28. The loss of that territory was a setback for protesters, whose ability to paralyze the city with road closures has weakened in recent days.