Opposition party supporters and police clashed in the Senegalese capital Dakar on Sunday after President Macky Sall announced the indefinite postponement of a presidential election set for February 25, sparking a wave of international concern.

Just a day before official campaigning was due to begin, Sall plunged the nation into the unknown, saying he intervened because of a dispute between the National Assembly and the Constitutional Court over the rejection of candidates.

Lawmakers are investigating two Constitutional Council judges whose integrity in the election process has been questioned.

“I will begin an open national dialogue to bring together the conditions for a free, transparent and inclusive election,” Sall said, without providing a new date.

Heeding the call of some opposition candidates, hundreds of men and women of all ages, waving Senegalese flags or wearing the jersey of the national football team, converged in the early afternoon at a roundabout on one of the capital’s main roads.

Police responded with tear gas and then pursued the fleeing protesters through adjoining streets, while some demonstrators responded by throwing rocks.

Under Senegal’s election code, at least 80 days must pass between publication of the decree setting the date and the election, so the earliest a vote could now be held is late April.