Police in Pakistan's largest city came under fire in what appears to be two, separate attacks – one targeting a top police official.

Police say a district police chief escaped unharmed Thursday after a suicide bomber blew himself up next to his vehicle. At least five people were wounded.

Elsewhere in Karachi Thursday, unidentified gunmen attacked a police patrol, killing three officers.

A doctor at Karachi's Jinnah Hospital said the dead included one sub-inspector and two constables.

Sectarian violence has been blamed for the deaths of hundreds of people in Karachi in recent years. Many of the killings are blamed on ethnic gangs linked to rival political factions such as the majority Urdu-speaking MQM and the Awami National Party of Pashtun migrants.