COLOMBO, Sri Lanka—A series of blasts tore through churches and luxury hotels in Sri Lanka on Easter morning, killing at least 290 people and wounding more than 400 in coordinated attacks on tourists and the country’s minority Christian community.

At least eight explosions, most blamed on suicide bombers, took place across the country. Restaurants and houses of worship that moments earlier were hosting holiday feasts and joyful services were plunged into chaos, filled with rubble, broken furniture, shards of glass and the...