SEVEN PEOPLE DIED and 33 suffered injuries when a public bus with 60 people aboard overturned Tuesday in the southern Chinese province of Guangdong, according to a report reaching the capital Wednesday. The bus was on its usual route when the driver tried to take a high-speed turn, catapulting the vehicle into a muddy pit, the report said . . . AN EXPLOSION Wednesday at an oil field operated by American Caltex Pacific Indonesia in East Sumatra injured at least 60 people, including 45 oil-company workers and 15 villagers. The cause of the blast in a dynamite warehouse at Caltex's Duri oilfield was not immediately known.