The Saudi-led coalition battling Iran-backed rebels in Yemen said Tuesday that a ceasefire had begun at noon (0900 GMT) as scheduled.
Coalition spokesman Brigadier General Ahmed al-Assiri confirmed that the truce had taken effect. The rebel forces have yet to say if they will abide by the ceasefire.
It coincides with the start of United Nations-brokered talks in Switzerland between Yemeni government and rebel representatives.
Shortly after the ceasefire began, mortar rounds hit pro-government forces south of the flashpoint city of Taez, a Yemeni security official said.
"Five mortar rounds hit positions of the legitimate forces in Shuraija after the truce entered into effect," said police officer Taha al-Subhi.
Residents in Taez reported hearing shelling in the city.
The coalition said earlier that the truce followed a request by Yemeni President Abedrabbo Mansour Hadi, but warned it "reserves the right to respond in case of any violation" by the rebels.
In May a five-day pause in fighting proposed by Saudi Arabia allowed some aid into Yemen before the coalition resumed air strikes, blaming ceasefire violations by the Iran-backed Huthi rebels.
Under the Hadi government's ceasefire plan, a seven-day truce "would be renewed automatically if the other party commits to it", the coalition statement carried by the Saudi state news agency SPA cited Hadi as saying.
The coalition began air strikes in March after the Huthis and their allies overran much of Yemen. It later sent in ground troops.