A powerful explosion likely triggered by a gas leak ripped through a restaurant in downtown Rio de Janeiro early Thursday, leaving three people dead and 17 injured, the Brazilian city's mayor said.

Three of those hurt were in serious condition, Mayor Eduardo Paes told reporters at the scene of the explosion, which occurred around 7:30 am (1030 GMT).

Two suspicious packages delivered to Swedish government buildings triggered bomb scares Thursday, police said, amid reports one may have been a gift from Uruguay's visiting president.

Police were alerted to a suspicious letter or package at the Rosenbad building, which houses Prime Minister Fredrik Reinfeldt's offices, late Thursday morning and decided to evacuate parts of the building and cordon off the surrounding block, Stockholm police spokesman Ulf Lindgren told AFP.

Somali Islamist Shebab rebels on Thursday kidnapped two female Spanish aid workers from Kenya's Dadaab refugee camp, a regional police official said.

"Two aid workers of Spanish nationality have been kidnapped by the Shebab, they are working for MSF (Medecins Sans Frontieres)," Leo Nyongesa, regional police chief, told AFP.

British Foreign Secretary William Hague said Thursday that an alleged Iranian-backed plot to kill the Saudi envoy to the United States is a "major escalation in Iran's sponsorship of terrorism."

Hague said London was in "close touch" with U.S. authorities and would work to agree an international response along with the United States, European Union and Saudi Arabia to the U.S. charges, which Tehran denies.

At least 43 people were killed Thursday when a bus veered off a mountain road in eastern Nepal and plunged into a river, officials said.

The bus swerved off an unfinished stretch of road and plummeted 300 meters into the fast-flowing water below, said Lokendra Shrestha, a police officer in Sindhuli district, around 80 kilometers east of Kathmandu.

An Amtrak train crashed into another train unloading passengers in an Oakland station late Wednesday, injuring 16 people, authorities said.

The train was traveling an estimated 15 to 20 miles per hour when it struck the stationary Amtrak passenger train about 10 p.m., said Oakland Fire Department battalion chief Emon Usher.

Two U.S. drone strikes on Thursday killed at least 10 militants in Pakistan's northwestern tribal belt, including a commander in the al-Qaida-linked Haqqani network, local officials said.

The first strike targeted the Haqqani commander in North Waziristan, killing him and three guards, while a second attack hit the Birmal area in the neighboring district of South Waziristan close to the Afghan border.

Amnesty International called on Canadian authorities Wednesday to arrest and prosecute George W. Bush, saying the former U.S. president authorized "torture" when he directed the U.S.-led war on terror.

Bush is expected to attend an economic summit in Surrey in Canada's westernmost British Columbia province on October 20.

A Nigerian man dubbed the "underwear bomber" pleaded guilty Wednesday to trying to blow up a U.S.-bound airliner on Christmas Day 2009, saying he had sought to avenge the killing of Muslims.

In a six-minute speech to a shocked courtroom on the second day of his high profile-trial in Detroit, Michigan, Umar Farouk Abdulmutallab insisted his actions were righteous and that the true crime was U.S. foreign policy.

A 6.0-magnitude earthquake struck off the Indonesian island of Bali Thursday, causing panic in tourist areas as people fled buildings that cracked as they shook violently in the tremor.

The U.S. Geological Survey (USGS) said the quake's epicenter was in the ocean south of Bali's capital Denpasar, but the Hawaii-based Pacific Tsunami Warning Center said there was no current tsunami warning in effect.