Heavy rain lashed Visakhapatnam since early this morning. Cumulonimbus cloud formation plunged the city into darkness and rain accompanied by thunder, lightning and gusty winds caused havoc. Several wall collapses were reported from all over the city after the rain stopped. In fact thundershowers are causing havoc in North Andhra Pradesh (AP) from the past few days. The weather is likely to continue in this manner, state meteorological officials said. It is because of cyclonic storms in the Bay of Bengal, spreading over east and northeast of the country, they added.