LAGOS, NIGERIA — Terror attacks across Nigeria by a radical Muslim sect killed at least 39 people, with the majority dying on the steps of a Catholic church after celebrating Christmas Mass as blood pooled in dust from a massive explosion.

Authorities on Sunday acknowledged they could not bring enough emergency medical personnel to care for the wounded outside St. Theresa Catholic Church in Madalla near Nigeria’s capital. Elsewhere, a bomb exploded amid gunfire in the central Nigeria city of Jos, and a suicide car bomber attacked the military in the nation’s northeast as part of an apparently coordinated assault by the sect known as Boko Haram.

The Christmas Day violence, denounced by world leaders and the Vatican, shows the threat of the widening insurrection posed by Boko Haram against Nigeria’s weak central government. Despite a recent paramilitary crackdown against the sect in the oil-rich nation, it appears that Africa’s most populous nation remains unable to stop the threat.

The White House condemned what it called a “senseless” attack, offered its condolences to the Nigerian people and pledged to assist authorities in bringing those responsible to justice.

In a statement, Britain’s Foreign Secretary William Hague said, “These are cowardly attacks on families gathered in peace and prayer to celebrate a day which symbolizes harmony and goodwill towards others.”

U.N. Secretary General Ban Ki-Moon called in a statement for an end to sectarian violence in the country.

The first explosion on Sunday struck St. Theresa Catholic Church just after 8 a.m. The attack killed 35 people and wounded another 52, said Slaku Luguard, a coordinator with Nigeria’s National Emergency Management Agency.

Though billions of dollars of oil money flow into the nation’s budget yearly, Luguard’s agency could only send text messages to journalists asking for their help in getting more ambulances.

Those wounded filled the cement floors of a nearby government hospital, with television images showing them crying in pools of their own blood. Corpses lined an open-air morgue.

The bombing and the delayed response drew anger from those gathering around the church after the blast. The crowd initially blocked emergency workers from the blast site, only allowing them in after soldiers arrived.

“We’re trying to calm the situation,” Luguard said. “There are some angry people around trying to cause problems.”