Authorities found five burned bodies in a bank in Al Hoceima set ablaze by anti-government protesters during the weekend.
Waves of unrest are sweeping across much of the Middle East after protesters brought down the governments of Tunisia and Egypt.
Moroccan Interior Minister Taib Cherkaoui said demonstrators calling on King Mohammed VI to diminish his authority were peaceful, though there were reports of looting, the BBC reports.
There were no indications how those in the bank were killed. Morocco, unlike other parts of the Middle East, has a stable economy run by an elected Parliament. The government there, the BBC adds, is unlikely to follow the same path as Tunisia and Egypt.
Much of the population in the Arab world, however, is under the age of 30, a demographic hit hard by unemployment. BBC correspondents add the income gap between the wealthiest and the poorest in Morocco is "obscene."
King Mohammed VI is part of a dynasty ruling over Morocco for more than three centuries. His family claims they are direct descendants of the Islamic Prophet Mohammed.