DHAKA, Bangladesh (AP) — Police in Bangladesh said Sunday that they were investigating the possibility a local radical Islamic group was behind two attacks on publishing houses in the capital this weekend that left a publisher of secular books dead and another critically wounded.

The banned group Ansarullah Bangla Team is the main focus of an investigation into Saturday's attacks, Munirul Islam, a senior police detective, told reporters. The two publishers who were apparently targeted in the attacks had links to a blogger who was killed earlier this year in an attack claimed by Ansarullah Bangla Team.

"Our focus is on those who work under the umbrella of Ansarullah Bangla Team," Islam said.

Publisher Faisal Arefin Deepan was hacked to death in his Dhaka office in the second attack Saturday. The first attack left publisher Ahmed Rahim Tutul in critical condition, while two writers suffered less serious wounds.

Deepan's Jagriti publishing house and Tutul's Shudhdhoswar had both published works of Bangladeshi-American blogger and writer Avijit Roy, who was hacked to death in February as he walked on the campus of Dhaka University with his wife.

Roy is one of four atheist bloggers murdered in Bangladesh this year. Ansarullah Bangla Team had claimed responsibility for all four of those attacks and recently threatened to kill more bloggers.

On Sunday, the English language Daily Star newspaper reported that another publisher — Farid Ahmed of Somoy publishing house — received a death threat for publishing the works of atheists. Ahmed could not be reached for comment.

Another militant group, Ansar al-Islam, the Bangladesh division of al-Qaida in the Indian Subcontinent, issued a statement Saturday claiming responsibility for the attacks on Deepan and Tutul, according to the SITE Intelligence Group, which monitors jihadist online postings. The claim of responsibility could not be independently verified.

Dozens of teachers, intellectuals and students rallied at Dhaka University on Sunday to protest Saturday's attacks.

Bangladesh has been rocked by a series of attacks this year claimed by Islamic extremists, including the blogger killings and, more recently, the killings of two foreigners — an Italian aid worker and a Japanese agricultural worker. An Oct. 24 bomb attack on thousands of Shiite Muslims in Dhaka killed a teenage boy and injured more than 100 other people.

The Islamic State group claimed responsibility for the attacks on the two foreigners and the bombing, but Bangladesh's government has rejected that the extremist Sunni militant group has any presence in the country.

The government has instead blamed domestic Islamist militants along with Islamist political parties — specifically the opposition Bangladesh Nationalist Party and its main ally, Jamaat-e-Islami — for orchestrating the violence to destabilize the impoverished nation.