Bangladeshi security forces appeared to gain the upper hand Monday in a four-day siege with heavily-armed militants reportedly backed by the Islamic State group in northeastern Sylhet city.
Since Friday, 12 people, including two policemen and four suspected militants, have been killed and 50 others injured in ongoing battles and bomb explosions, authorities say.
Police have used armored vehicles and fired bullets and tear gas in an attempt to end the standoff with militants holed up in a building and armed with guns, explosives and suicide vests.
"They threw grenades, exploded explosives and fired from inside," said police Brig. Gen. Fakhrul Ahsan. "They are well-trained and have thrown back the grenades we lobbed at them."
By late Monday, Bangladeshi media reported the building was cleared of armed assailants.
"We don't believe anyone else is inside," Ahsan told reporters.
Police were carefully combing the building, as it is booby-trapped with "many bombs," Ahsan said. He added that more than 75 civilians were evacuated from the building and the army was proceeding carefully to avoid civilian casualties.
"There is a large hold of explosives in the militants' den and the operation is continuing," he said.
The standoff began after a series of attacks throughout the country, including a suicide bombing on Friday when a man killed himself by detonating explosives near a police post on a busy road near the airport in Dhaka, Bangladesh's capital.
IS claimed responsibility for the attacks, according to the SITE Intelligence group, citing the Islamic State news agency Amaq. SITE monitors terror group activity online.
Bangladesh is facing growing domestic threats from a variety of militant and extremist groups, including IS and al-Qaida affiliates. Terror attacks in recent months have killed at least 70 Bangladeshis and some foreigners.
The Bangladeshi government has been denying that IS has a presence in the country, but analysts say some local militant groups receive support from IS and operate on its behalf in the country.
"For two attacks to happen in the same week and to have them claimed so quickly is a clear indication that there is an IS network in the country," Amarnath Amarasingam, an analyst at George Washington University's Program on Extremism, told VOA.
"Even as the politicians deny the existence of IS, it seems law enforcement is behaving like there is, in fact, something to worry about," Amarasingam said.
IS in the last year has claimed responsibility for several attacks, including the fatal shooting of Italian aid worker Cesare Tavella, 50, in Dhaka and an attack on a Bangladesh-based Italian pastor, Piero Parolari. IS also claimed responsibility for a suicide attack on a Shi'ite procession in the capital last year that killed two people and wounded dozens.
Zillur Rahman Khan, a professor emeritus from the University of Wisconsin Oshkosh and an expert in militancy in Bangladesh, told VOA that two former army majors who were dismissed by the army for "questionable activities" have been acting on behalf of IS in Bangladesh.
One of the officers was killed in a police operation earlier this year, according to Khan. The other officer remains at large, Khan said, and is directing IS-related activities.
VOA's Bangla service contributed to this report.