Scores of policemen have staged demonstrations in Egypt's Nile Delta to demand outstanding bonuses are paid and better employment benefits in a rare show of protest since President Abdel Fattah el-Sisi came to power last year.
Protesting officers closed six police stations in the province of Sharqiya and broke into the security directorate to protest against the authorities' failure to meet their demands.
"Protesters stormed the security directorate after [officials] called in riot police to disperse them," a security source told Turkey's Anadolu news agency.
Al-Ahram, a local newspaper, said the Central Security Forces fired tear gas to disperse lower-ranking police officers camping at the directorate.
The officers, who have been on strike since Saturday, responded by firing warning shots into the air, the newspaper said.
At least four people were reported injured in the clashes.
The police officers chanted slogans calling for the dismissal of the interior minister and the head of the Sharqiya security directorate.
The policemen have been demanding the payment of bonuses for the months of June and July, along with access to the same hospitals used by higher-ranking officials.
An unnamed security source, quoted by state news agency MENA, accused the protesting police of being funded by the outlawed Muslim Brotherhood group - a claim dismissed by the protesters.
The source said the interior ministry "will take the necessary legal action against those who incited and participated in the strike".
Since the 2013 ousting of Mohamed Morsi, Egypt’s first democratically elected president and a Brotherhood leader, Egyptian authorities have mounted a harsh crackdown on the group, arresting nearly its entire leadership.
A controversial law issued in November 2013 outlawed all unlicensed protest activity in Egypt.
The striking police have won the support of colleagues from a number of other cities.
The lower-ranking policemen's club in Alexandria released a statement, quoted by Al-Ahram, supporting their colleagues in Sharqiya and calling on Sisi to intervene in order to end the ongoing crisis.
In February 2014, policemen protested in Alexandria and Kafr El-Sheikh to demand higher wages and better working conditions, the newspaper said.
Two weeks ago, hundreds of civil servants protested in Cairo against a new law regulating their conditions of employment.
It was one of the largest demonstrations the capital has seen since the November 2013 protest law.