Persistent heavy rain and landslides in Wenchuan County and the nearby area badly affected rescue efforts. At the start of rescue operations on May 12, 20 helicopters were deployed for the delivery of food, water, and emergency aid, and also the evacuation of the injured and reconnaissance of quake-stricken areas.
Many rescue teams, including that of the Taipei Fire Department from Taiwan, were reported ready to join the rescue effort in Sichuan as early as Wednesday. However, the Red Cross Society of China said that (on May 13) "it was inconvenient currently due to the traffic problem to the hardest-hit areas closest to the epicenter".
Beijing accepted the aid of the Tzu Chi Foundation from Taiwan late on May 13. Tzu Chi was the first force from outside the People's Republic of China to join the rescue effort.
By May 14, the Ministry of Civil Affairs stated that 10.7 billion yuan (approximately US$1.5 billion at that time) had been donated by the Chinese public.
On the afternoon of May 14, 15 Special Operations Troops, along with relief supplies and communications gear, parachuted into inaccessible Mao County, northeast of Wenchuan.
By May 15, Premier Wen Jiabao ordered the deployment of an additional 90 helicopters, of which 60 were to be provided by the PLAAF, and 30 were to be provided by the civil aviation industry, bringing the total number of aircraft deployed in relief operations by the air force, army, and civil aviation to over 150, resulting in the largest non-combat airlifting operation in People's Liberation Army history.
On May 16, China stated it had also received $457 million in donated money and goods for rescue efforts so far, including $83 million from 19 countries and four international organizations. Saudi Arabia was the largest aid donor to China, providing close to €40,000,000 in financial assistance, and an additional €8,000,000 worth of relief materials.
On the evening of May 18, CCTV-1 hosted a special four-hour program called The Giving of Love, hosted by regulars from the CCTV New Year's Gala and round-the-clock coverage anchor Bai Yansong. It was attended by a wide range of entertainment, literary, business, and political figures from mainland China, Hong Kong, Singapore, and Taiwan. Donations of the evening totaled 1.5 billion Chinese Yuan (~US$208 million). Of the donations, CCTV gave the biggest corporate contribution at ¥50 million.
The State Council declared a three-day period of national mourning for the quake victims starting from May 19, 2008; the PRC's National Flag and Regional Flags of Hong Kong and Macau Special Administrative Regions flown at half-mast. It was the first time that a national mourning period had been declared for something other than the death of a state leader, and many have called it the biggest display of mourning since the death of Mao Zedong.
Strong aftershocks continued to strike even months after the main quake. On May 25, an aftershock of 6.0 Mw (6.4 Ms according to CEA) hit northeast of the original earthquake's epicenter, in Qingchuan County, Sichuan.
As a result of the earthquake and the many strong aftershocks, many rivers became blocked by large landslides, which resulted in the formation of "quake lakes" behind the blockages; these massive amounts of water were pooling up at a very high rate behind the natural landslide dams and it was feared that the blockages would eventually crumble under the weight of the ever-increasing water mass, potentially endangering the lives of millions of people living downstream. As of May 27, 2008, 34 lakes had formed due to earthquake debris blocking and damming rivers, and it was estimated that 28 of them were still of potential danger to the local people. Entire villages had to be evacuated because of the resultant flooding.