A rainstorm with winds of more than 60 mph battered northern Bangladesh, injuring more than 100 people and leaving an estimated 15,000 people homeless, police said today. Police at Rangpur, 80 miles north of Dhaka, said by telephone that the storm Wednesday destroyed at least 3,000 mud-and-straw huts, uprooted hundreds of trees and downed electrical lines. Thousands of acres of rice paddy were damaged, they added. Most of the injuries were caused by collapsing huts or flying tree limbs and other debris, they said. About 20 people were reported in critical condition. Police said 15,000 people, most of them poor farmers, were homeless. Rainstorms with high winds are common during summer months in Bangladesh. In the past two weeks, storms in several areas, including the capital of Dhaka, have claimed more than a dozen lives and injured several hundred people.