(AP) -- Bangladesh has been rocked this year by a series of deadly attacks claimed by radical Islamist groups, raising concerns about growing extremism in the mostly Sunni Muslim nation. Following is a list of the attacks.
— Feb 27: At least two assailants attack Bangladeshi-American blogger and writer Avijit Roy with meat cleavers, killing him and injuring his wife on a crowded street in Dhaka, the capital. A previously unknown group, Ansar Bangla 7, which intelligence officials believe is part of the banned Ansarullah Bangla Team, claims responsibility. At least four suspects are arrested.
— March 30: Three men use meat cleavers to hack 26-year-old blogger Washiqur Rahman Babu to death in Dhaka. Bystanders chase down two of the attackers, but a third escapes. The captured suspects say they are students at Islamic schools and were ordered to commit the crime. Police have been unable to determine who gave the order.
— May 12: Four men with meat cleavers kill online atheist activist and science magazine editor Ananta Bijoy Das as he leaves his home in the northeastern city of Sylhet. Police arrest a newspaper photographer and two others. Al-Qaida on the Indian subcontinent, which is believed to be affiliated with Ansarullah Bangla Team, claims responsibility.
— Aug. 8: A fourth blogger, Niloy Chottopadhay, is killed by men who enter his Dhaka apartment, posing as potential tenants, and assault him with cleavers. Ansarullah Bangla Team claims responsibility in an email, though the authenticity of the message has not been confirmed.
— Sept. 28: Three assailants on a motorcycle gun down Italian citizen Cesare Tavella in Dhaka's diplomatic quarter. The Sunni extremist group Islamic State claims responsibility, according to the terror monitoring group SITE. Officials reject the claim and accuse local Islamist groups of attempting to destabilize the country. A month later, police arrest four suspects who say they were hired by "a big brother" to attack "a white man" to create chaos in the country, according to authorities.
— Oct. 4: Masked assailants on a motorcycle kill Japanese citizen Kunio Hoshi, who was working in agriculture in northern Bangladesh. The Islamic State group claims responsibility, but the government again dismisses the idea that the group has any presence in the country.
— Oct. 24: Attackers hurl homemade bombs into a crowd of thousands of Shiite Muslims as they gather for a predawn religious procession in Dhaka. A teenage boy is killed and more than 100 other people are injured. Police arrest two suspects and recover two unexploded bombs. They dismiss an IS claim of responsibility and say the culprits were likely from the banned local group Jumatul Mujahedeen Bangladesh. On Nov. 26, security forces arrest six suspects after a gunfight that killed the group's alleged military commander.
— Oct. 31: A group of men hack a publisher of secular books to death and injure three others in Dhaka. The publisher, Faisal Arefin Deepan, had close ties with murdered blogger Roy. The banned group Ansar al-Islam claims responsibility.
— Nov. 26: At least five gunmen open fire on Shiite Muslim devotees during evening prayers at a mosque in northern Bangladesh. An elderly mosque official who had been leading the prayers is killed and three others are injured. A group describing itself as an IS affiliate in Bangladesh claims responsibility and vows more attacks. Police detain two suspects for questioning.