QUETTA, Pakistan — A remotely-detonated bomb killed three workers doing a survey for a local oil exploration company in southwestern Pakistan on Tuesday, police said.

Local police official Mohammad Hussain said the bombing near the town of Dera Bugti in the Baluchistan province also wounded five surveyors.

There was no immediate claim of responsibility, but small nationalist groups and separatists have claimed previous such attacks in the province. Islamic militants also have a strong presence in Baluchistan.

The latest violence came a day after assailants ambushed a convoy of paramilitary troops, killing six of them in the Awaran district of Baluchistan. No group has claimed that attack either.

Baluch separatists have staged attacks for years, demanding a larger share of provincial resources and wealth or complete autonomy from Islamabad.

In a separate incident on Tuesday, a grenade was thrown at the election office of a candidate running for a seat in parliament, wounding 10 people, according to Ayaz Khan, an assistant commissioner in the town of Ramzak, in the northwest near the Afghan border.

He said the candidate, Aurang Zeb, who is from the party of former cricket star Imran Khan, was not present at the time of the attack.

It was the first violent incident ahead of the July 25 vote.