Police say the attacker is in custody after he was shot and wounded for failing to put down his knife.

Officers were called to the centre just before 11am (10:00 GMT) on Tuesday where they encountered a man “armed with a large knife”, read a police statement.

The suspect has been taken into custody after he was shot by police because he did not obey warnings to put down his weapon.

Two female employees, aged 49 and 24, of the Ismaili Centre, located not far from the Benfica Lisbon football stadium, were killed in the attack, according to a report from TV station RTP.

A police spokesman told the dpa news agency that the deceased had not yet been officially identified and that a “terrorist attack” was suspected, but without ruling out other motives.

Local media reported that the attacker was a widowed Afghan refugee and a father to three children. Al Jazeera could not independently confirm the identity of the attacker.

Prime Minister Antonio Costa expressed his condolences and solidarity to the families of the victims and also to the Ismaili community in Portugal on Twitter.

It is too early to speculate about the motives for this crime, said Costa. “We have to wait for the results of the investigation,” he said.

Later in the day, Interior Minister Jose Luis Carneiro, said that “everything leads to believe” that the attack was “an isolated act”.

Portugal has been considered one of the safest countries in the world and does not tend to experience Islamophobic attacks or generally a high level of crime.

Prince Karim Aga Khan, spiritual leader of the world’s Ismailis, opened the Lisbon centre in 1998. It has exhibition spaces, classrooms and prayer halls.

There are approximately 7,000 Ismaili Muslims living in Portugal, a nation of about 10 million people. The Ismailis belong to the Shia branch of Islam.

Many fled to Portugal from Mozambique, a former Portuguese colony during the African country’s civil war which ended in 1992.