ABUJA, Nigeria — Twin suicide bombings at a mosque and at a market have left at least 27 people dead and scores wounded in northeastern Nigeria, leading the authorities on Wednesday to tighten security in the region, which has been targeted repeatedly in recent years by Boko Haram, the rebel Islamist insurgency.

The bombings took place around 1 p.m. on Tuesday during afternoon prayers in Mubi, a town roughly 120 miles north of Yola, the capital of Adamawa State. The suicide bombers, two young men, detonated a first bomb after prayers began and a second one outside as people fled, according to the police.

Usman Abubakar, a local police spokesman, said 27 people were killed and 58 were wounded by the suicide bombers, which he said were believed to have been Boko Haram militants.

“For a long time we haven’t experienced anything on this scale,” Mr. Abubakar said.

Some news reports, citing local residents and witnesses at burial ceremonies, said the death toll could be much higher, with over 60 victims. The news agency Agence France-Presse quoted gravediggers as saying that they had buried 86 bodies after the bombings, but it was not immediately possible to verify that figure.