Xinhua world news summary at 1530 GMT, May 1

BUJUMBURA -- At least 15 persons were injured in a grenade explosion that happened on Monday night in Kayanza province, northern Burundi, a police spokesman said Tuesday.

An unidentified criminal blasted a grenade around 7 p.m. at Karurusi village in Gatara district, said Burundian Police Spokesman Dismas Manirakiza, adding that seven of the injured were wounded seriously. (Burundi-Grenade Explosion)

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SAO PAULO -- An abandoned office building in the center of the southeastern Brazilian city of Sao Paulo collapsed Tuesday after catching fire, leaving at least one person dead, according to local authorities.

The collapsed building, once a police facility, was inhabited intermittently by squatters several years ago. It caught fire at around 1:30 a.m. local time (0430 GMT) and collapsed a few hours later. (Brazil-Fire-Death)

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HAVANA -- Cuba's ruling party leader Raul Castro and President Miguel Diaz-Canel on Tuesday together chaired the central event to mark the International Workers' Day in the capital of the Caribbean island state.

They chaired the rally held at the Revolution Plaza in Havana, where thousands of workers and their families had gathered since early morning. The celebrating event was organized by the Confederation of Cuban Workers with the slogan "Unity, Commitment and Victory." (Cuba-Labor Day)

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DAMASCUS -- The U.S.-backed Syrian Democratic Forces (SDF) declared on Tuesday the beginning of a new offensive against the Islamic State (IS) militants in the countryside of the eastern province of Deir al-Zour, the SDF said in a statement.

The battle was launched against the areas under the IS control on the eastern bank of the Euphrates River in Deir al-Zour, said the statement, adding that it's a follow-up offensive against IS near the Iraqi border. (Syria-IS) Enditem