US Attorney General Eric Holder confirms four American citizens have been killed in US drone strikes in Yemen and Pakistan since 2011.

Micro-blogging site Twitter says it is bringing in a two-step login for users to beef up security following recent high-profile breaches.

The mayor of the tornado-devastated town of Moore in Oklahoma has vowed to push for a new law on shelters, after a huge twister there killed at least 24.

Ripley's oddballs and oddities prepared the world for reality TV

A Florida man was shot and killed as he became violent under questioning by Boston bombing investigators, FBI officials say.

More than one million Montreal residents must boil drinking and cooking water after a mishap at a water treatment plant, officials warn.

Hewlett-Packard shares leap in after-hours trading, despite quarterly results showing a seventh consecutive fall in sales.

The mayor of the tornado-devastated town of Moore in Oklahoma vows to push for a new law on shelters, after Monday's deadly twister.

The US tax official at the centre of a furore over the agency's targeting of conservative groups invokes her right to silence when questioned by Congress.

Airbnb tells its members "we are not going anywhere", after a judge in New York ruled a man who rented out his apartment on the site broke the law.

US Federal Reserve chairman Ben Bernanke tells Congress that it is too soon to end the stimulus programme or raise interest rates.

By a wide margin, Los Angeles elects its first Jewish mayor, Eric Garcetti, a 42-year-old three-term city councilman.

Getting ready for bookless libraries

The damage from the Oklahoma tornado could reach $2bn (£1.3bn), the Oklahoma Insurance Department warns, although many tenants may have no insurance cover.

A former congressman who resigned in disgrace in 2011 over his racy Twitter messages has announced he will run for mayor of New York City.

The rescue effort after the Oklahoma twister that killed 24 people nears an end, as it emerges the storm was more powerful than thought.

Tiger Woods condemns "hurtful" jibe as Sergio Garcia apologises for what could be interpreted as a racist remark.

The inventor of the Gif image format says it should be pronounced Jif, despite what the Oxford English Dictionary says.

Footage filmed by Charles Gafford shows the power of the tornado in Oklahoma, seen through the opening of a roof inside a storm shelter.

The Solar Impulse plane, which holds records including the longest manned zero-fuel flight, sets off on the second leg of a bid to cross the US.