Rabat, Morocco (CNN) -- Morocco's Interior Ministry said Thursday that three Moroccan suspects loyal to al Qaeda have been arrested in connection with last month's bombing at a popular Marrakech cafe, the official Maghreb Arabe Presse news agency reported.
One of the suspects was described in the Interior Ministry statement as the main figure in the April 28 bombing that killed 16 people and injured 21, according to the MAP report. The ministry statement described the bombing as a terrorist attack.
The bombing occurred around 11 a.m. at Cafe Argana in Marrakech's old city, which is designated by the United Nations' cultural arm as a World Heritage Site. Tourists flock to the old city this time of the year, and it is usually packed with stalls, storytellers and snake-charmers.
World leaders, including U.N. Secretary-General Ban Ki-moon and U.S. Secretary of State Hillary Clinton, condemned the bombing.
"The individuals were absorbed by jihadist ideology, and had allegiance to al Qaeda and had already made several attempts to join some of the hotbeds of tension, especially Chechnya and Iraq, before deciding to carry out terror in the homeland," the ministry statement said, according to MAP.
The suspects learned on the Internet how to make the two remote-detonated explosive devices used in the bombing, the ministry statement said. The attackers chose Cafe Argana as the target because of its popularity, and dressed as tourists to access the area, the statement said.
A preliminary investigation found remnants of explosive materials and tools "that had been discarded after the terrorist act," according to the statement.
CNN's Mitra Mobasherat, Salma Abdelaziz and journalist Martin Jay contributed to this report