Gunmen in Pakistan have shot dead a former journalist near his home in Karachi, the third such attack on media personnel in less than 24 hours.

Aftab Alam had worked with the country's largest private broadcaster Geo News.

On Tuesday night, gunmen shot at Geo TV's news van in Karachi, killing a technician and injuring the driver.

A journalist with national broadcaster PTV was also seriously injured when he was shot in an attack in Peshawar.

Police said the motives behind the shootings were not immediately clear, the BBC's M Ilyas Khan in Islamabad reports.

Aftab Alam was on his way to pick up his children from school when he came under attack from gunmen on a motorcycle.

He had most recently worked for another leading Urdu-language TV news channel, Samaa, but was not currently employed in the profession.

Pakistan's financial capital has seen a spate of attacks on the media.

Arshad Ali Jaffery was named as the Geo News TV technician killed in Tuesday night's drive-by shooting.

In April last year one of Geo's main presenters, Hamid Mir, was seriously injured in a shooting in Karachi. His family blamed the attack on the country's spy agency, the ISI.

In January 2014 three Express Media staff were killed. One of its news anchors narrowly escaped in another shooting two months later but his driver was killed.

Two gun and bomb attacks on the group's office in the city the previous year left at least four people injured.

According to the International Federation of Journalists, Pakistan was the world's most dangerous country for the media in 2014, with 14 journalists killed.