Swedish police arrested three Somali men and an Iraqi Saturday night on suspicion they were plotting to attack an art fair at a landmark gallery in Goteborg.

There is speculation that cartoonist Lars Vilks, whose caricature of the prophet Mohammed as a dog generated radical Islamist outrage may have been planning to attend. A local news agency reported the suspects were arrested near the fair. More than 300 people were evacuated from the event late Saturday night by police "after concluding that there was a threat that could endanger lives or health or cause serious damage."

Another local report indicated the attack involved bombs and guns. The three Somalis are suspected of being tied to the Somali terrorist group al-Shebaab, which vowed to retaliate against Vilks. Other reports indicate two of the suspects are Swedish citizens.

Officials are saying very little about the case. Prosecutors have until Tuesday to decide whether to charge the suspects or release them.