CALCUTTA, India, Nov. 30 (AP)—Sirens sounded a practice air‐raid alert tonight and for half an hour this city of seven million people was effectively blacked out.

Automobiles, trucks and buses crawled through the teeming streets with head lights off. The lights went off in shop windows and on market stalls and there was a brisk trade in flashlights and candles.

Car stickers appeared in: Calcutta bearing the legend: “Liberate Bangla Desh, Punish Yahya Khan, Finish Pakistan.”