Cyclonic storm Laila finally struck the Andhra coast 50 km north of Bapatla town of Guntur district on Thursday afternoon.
The coastal belt of Andhra Pradesh from Nellore to Krishna was being battered by very heavy-to-heavy rains and gale winds of 90 to 100 km per hour.
The regions of Ongole, Bapatla, Chirala, Avanigadda, and Nagayalanka will be immediately affected by the storm.
The storm hit the coast at around 1.15 pm on Thursday.
The Indian Meteorological Department said the storm will cross the coast into the main land in two hours.
Chief Minister K Rosaiah said, "If we are lucky the losses will be lesser."
He said the wind speed was less than what was earlier forecast. "But it still has the potential to cause havoc."
Rosaiah said the region was receiving very heavy rains and Ongole in Prakasham district had alone has recorded 32 cm of rainfall on Thursday morning.
Normal life came to a standstill in the region as power supply was disrupted in 11 major towns and 1,492 villages, he added.
Over 40,000 people had been evacuated from low-lying areas of Andhra Pradesh.
Defence Minister A K Antony said, "The armed forces were always ready to help the civil administration whenever they are in distress."
"Whatever help is needed from the Navy and the other armed forces, we will extend," he said.
Scattered heavy-to-very heavy rainfall and isolated extremely heavy fall of 25 cm or more is likely over coastal Andhra and north Tamil Nadu, according to the IMD.
A gale speed of 115 to 125 km per hour is expected to blow along and off AP coast at the time of landfall, it said.
The entire coastal belt has been gripped with fear as the state government said 12 lakh people would be directly affected by the storm, which is being described as the worst since the 1977 hurricane that killed 10,000 people in Krishna district.
The Andhra coastal belt from Nellore to Visakhapatanam, parts of Rayala Seema and Telangana region have been receiving heavy rains since two days.
Tada in Nellore, bordering Tamil Nadu, received the highest rainfall of 13 cm in the last 24 hours, the Met office in Hyderabad said.
Rain-related death toll rose to 15 on Wednesday of which seven were due to house collapses and the rest due to drowning.
State revenue minister Dharmana Prasad Rao said more than 1,100 villages have been identified as vulnerable and the residents were being evacuated. About 500 relief camps haave been opened in six districts and food and other essential commodities were being provided to them, he said.
The National Disaster Management Authority has sent a team of experts and more than 500 personnel of the National Disaster Response Force to areas of potential disaster with 80 inflatable boats and other rescue equipment.
The Eastern Naval Command of Indian Navy at Visakhapatanam has been put on alert and about 100 armymen have been stationed at the Vijaywada airport. The navy and army services said they would press the helicopters to service only after the storm hit the coast.
The IMD had forecast that after crossing the coast, Laila would move in northeasterly direction and after passing over Visakhapatanam and Vizianagaram it was likely to weaken over Balasore in Orissa, reenter Bay of Bengal and head towards Chittagong in Bangladesh.
Officials fear the cyclone would have a crippling impact on the state economy, as the rains have already destroyed the standing crop of rice, banana and mangoes over thousands of acres in the coastal region.
With inputs from agencies
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