DHAKA, Bangladesh (AP) — With a strong cyclone approaching Bangladesh on Saturday, authorities used more than 50,000 volunteers and officials to evacuate hundreds of thousands of people to shelters across the low-lying delta nation's vast coastal region.

More than 300,000 people had already moved to safer places and up to 1.8 million were expected to be evacuated by the evening, said Enamur Rahman, Bangladesh's junior disaster management minister.

Cyclone Bulbul was moving over the Bay of Bengal and was expected to hit the country's southwestern and southern coasts on Saturday evening. More than 5,000 shelters had been prepared by the morning.

The weather office in Dhaka, the capital, issued the most severe storm signal for Bulbul, which was packing maximum sustained winds of 74 kilometers (46 miles) per hour and gusts of up to 150 kph (93 mph).

It said the southwestern Khulna region could be the worst hit. The region has the world's largest mangrove forest, the Sundarbans.

The weather office said coastal districts were likely to be inundated by storm surges of 1½-2 meters (5-7 feet) above normal tide because of the impact of the approaching cyclone.

Several ships from Bangladesh's navy and coast guard were kept ready in parts of the region for any emergency response, said the domestic TV station Independent.

The storm is also expected to impact parts of northeastern India, where precautions were also being taken.

According to U.S.-based AccuWeather Inc., Bulbul strengthened from a deep depression into a tropical cyclone on Thursday morning, and by Friday afternoon had strengthened into a severe cyclone.

With winds around 130-140 kph (80-87 mph), Bulbul is currently the equivalent of a Category 1 or 2 hurricane in the Atlantic, it said.

Rahman said government offices suspended work in 13 coastal districts on Saturday.

As the day progressed, the volunteers used loudspeakers to ask people to move to shelters in Chittagong and other regions, according to the ministry. In the Cox's Bazar coastal district, tourists were alerted to stay in their hotels while a few hundred visitors were stuck on Saint Martins Island.

Authorities suspended all activities in the country's main seaports, including in Chittagong, which handles almost 80% of Bangladesh's exports and imports. All vessels and fishing boats were told to stop operating.

Local authorities ordered school buildings and mosques to be used as shelters in addition to dedicated cyclone shelters — raised concrete buildings that have been built over the past decades.

Bangladesh, a nation of 160 million people, has a history of violent cyclones. But disaster preparedness programs in recent decades have upgraded the country's capacity to deal with natural disasters, resulting in fewer casualties.