GUNTUR, Sept 28: Three persons including a police constable were drowned and four others are missing after a milk tanker was swept away in the swirling waters of Nerella rivulet at Vemavaram culvert on the outskirts of Phirangipuram in Guntur district today.The mishap occurred when the driver of the milk tanker carrying several villagers attempted to cross the rivulet. The Vemavaram culvert proves to be the nemesis of unwary motorists on the Guntur-Narasaraopet road during the flash floods. As many as 14 persons were killed when an APSRTC bus met with a similar accident at the same spot in August, 1996.Despite the culvert being accident prone, officials did not take any steps to forewarn motorists. There is no danger signboard on either side of the culvert. Only after the mishap occurred did the drivers stopped plying on the road. A large number of APSRTC buses and other vehicles were seen stranded on either side of the culvert.