What caused traffic congestion, three-hour delay towards Dubai?

The police issued traffic updates on social media.

Traffic came to a standstill for three hours on all streets, exits leading to Dubai on Monday morning. A traffic accident caused the massive congestion.  
The operation room received information about an accident on Sheikh Mohammed bin Zayed Road at 6.30 am. The accident occurred during the peak hours and paralysed the traffic movement in most of the internal roads in Sharjah, Lt Colonel Khalid Al Kay, Deputy Director of the Traffic and Patrol Department at Sharjah Police said. It led to the disruption of traffic, especially in Muwailih and industrial areas.  
The police intensified inspections in congested streets to organise the traffic. Motorists assumed the accident occurred in Sharjah and many calls were received on 901 to inquire about the situation.
The police notified the motorists through their social media platforms and radio channels about the accident. Alternative routes were suggested to avoid more vehicles being stuck in the delay.