The weather department has issued an alert of heavy to very heavy rainfall at isolated places in at least eight districts of Uttarakhand in the next four days, following which authorities were asked to stay alert to deal with any untoward situation. In view of the rain forecast, the weather department has asked tourists visiting the hilly areas and people living in the low-lying areas to remain alert. The Song river in Dehradun is flowing above danger level. The State Disaster Response Force (SDRF) has already started with the rescue work. Water level in many rivers of Uttarakhand have increased with Ganga breaching the warning level mark at both Haridwar and Rishikesh, sparking fear of floods among residents of low-lying areas.