Two suicide bombers killed themselves in an attack on US diplomatic offices in Morocco's commercial hub Casablanca today.
Police arrested a third bomber as he tried to flee the scene of the mid-morning attack on the US cultural centre and the nearby US consulate in an upscale district of the port city, where three suicide bombers struck four days ago.
They were also checking reports a suspected fourth bomber was at large but there was no immediate confirmation.
A senior police source said the bombers clearly intended to attack the buildings, indicating they were the first targeted suicide bombings of a recent series in the city.
"There is no doubt they aimed at the US targets. They made that statement with their own bodies," the source said.
He said the two were unable to get closer to the two buildings because of security fortifications.
Witnesses said the first blast happened about six metres from the cultural centre and the second went off about 20 seconds later 60 metres away from the consulate.
On Tuesday three suicide bombers killed themselves in a poor neighbourhood of Casablanca after police raided a safe house and shot dead a fourth bomber. They set off their explosives to avoid being captured by police.
The government said the bombers were linked to a ring dismantled last month, which included suicide bombers who planned to blow up foreign ships docking at Casablanca's port and hotels in Morocco's main tourist cities.
The Rabat government says the bombers were "home-grown" militants with no links to international networks.
However, analyst Miloud Belkadi said: "The bombing today underscores links with al Qaeda strategy focusing on US targets. They are different from the suicide bombers killing themselves in slums."
The killings of the suicide bombers followed bombings in neighbouring Algeria this week where 33 people were killed in attacks claimed by an Islamist armed group known as the al Qaeda Organisation on the Islamic Maghreb.