The toll from a string of deadly suicide bomb attacks in Sri Lanka has risen to 310, with several people dying of their injuries overnight, a police spokesperson said Tuesday.

Around 500 people were wounded in the blasts, Ruwan Gunasekera said in a statement.

He added that 40 people were now under arrest in connection with the attacks, which Sri Lanka’s government has blamed on a previously little-known local Islamist group, National Thowheeth Jama’ath.

Meanwhile, details have begun to emerge about some of the foreigners killed in the blasts.

The United States reported at least four Americans killed including a child and the Netherlands raised their toll to three.

A Danish billionaire lost three of his children in the attacks, a spokesperson for his company said.

Eight Britons, eight Indians and nationals from Turkey, Australia, France, Japan and Portugal, were also killed, according to Sri Lankan officials and foreign governments.

The suicide bombers hit three Colombo luxury hotels popular with foreign tourists – the Cinnamon Grand, the Shangri-La and the Kingsbury – and three churches: two in the Colombo region and one in the eastern city of Batticaloa.

Two additional blasts were triggered as security forces carried out raids searching for suspects.

Interpol said it was deploying investigators and specialists to Sri Lanka and the US State Department warned of possible further attacks in a travel advisory.