DHAKA (Reuters) - The wife of a senior Bangladeshi police official known for battling Islamist militants was stabbed and shot to death on Sunday, and machete-wielding assailants killed a Christian grocer in a separate incident.

Both attacks appeared to be the work of Islamist militants who have killed at least 30 people, including religious minorities, liberal bloggers and academics, since February last year, police said.

Three assailants riding a motorcycle stabbed and then shot Mahmuda Aktar, 33, while she was on her way to put her son onto a school bus near her home in the southeastern port city of Chittagong, police said.

“She was stabbed first. Then they shot her in the head three times,” Humayan Kabir, deputy police commissioner of Chittagong, told Reuters.

Her husband, police superintendent Babul Aktar, has played an important role in cracking down on militants in the region.

“Babul Aktar is an efficient police officer and played a key role in apprehending Islamists. They might have killed his wife because they failed to get him,” Interior Minister Asaduzzaman Khan told reporters.

Aktar, who was recently posted to police headquarters in the capital, Dhaka, busted several hideouts of the banned group Jamaat-ul-Mujahideen. His team also arrested one of the group’s leaders, who was later killed in a grenade blast during a police raid in October.

The government has launched a crackdown on militant groups who want to impose strict Islamic law on Bangladesh, whose population of 160 million are mostly moderate Muslims.

In Sunday’s other killing, Sunil Gomes, a 60-year-old shopkeeper, was hacked to death in his shop in the northern district of Natore, local police official Manirul Islam said.

Islamic State claimed responsibility for killing Gomes, according to the U.S.-based monitoring service SITE.

Islamic State and al Qaeda have claimed responsibility for many killings in the past but the government denies either group has a presence in Bangladesh and says home-grown radicals are responsible.

State Minister for Foreign Affairs Shahriar Alam told Reuters in an interview last month that Islamic State was trying to ride a wave of religious radicalization by falsely claiming killings, and said there was enough evidence implicating domestic militant groups.