The explosion occurred near the football stadium in the southern Yemeni port city of Aden , according to preliminary data, four people were killed, Reuters reported quoting witnesses.

So far any group operating in the region hasn't taken responsibility for explosion. Details of he incident are being specified, RIA Novosti  reported.

The opposition between the authorities of the country headed by president Abed Rabbo Mansour Hadi overthrown by Houthis and Shiite rebels has continued in Yemen since August, 2014. The Arab coalition led by Saudi Arabia which applies air strikes on positions of Houthis has been on Hadi's side since March of last year. According to the UN, as a result of military operations in Yemen more than 6,500 people were killed, about 30,000 were injured.

The truce entered into the  force in Yemen in the night from Sunday to Monday. Both parties to the conflict have officially declared their readiness to observe it. However, a few hours after the beginning of the truce, local residents reported about artillery fire, air strikes and gun battles in several parts of the country.