Monday, May 29, 2006; Posted: 6:49 a.m. EDT (10:49 GMT)

Meanwhile Indonesia's president has acknowledged a "lack of coordination" as the first aid trickled into the quake-stricken zone on Java island.

Visiting refugees on Monday, The Associated Press quoted President Susilo Bambang Yudhoyono as calling for government officials to be "more agile."

The quake, which struck early Saturday morning close to the former Javanese royal capital of Yogyakarta, has so far killed 5,136 people, wounded nearly 6,504 and left 100,000 homeless.

Heavy rain added to the misery Monday as grieving survivors scavenged for food in the debris of their houses. Rescuers are being hampered by rain, power outages and the closure of a local airport.

"I saw in many areas that there are many things that need to be speeded up," the president said, after declaring a state of emergency to quicken relief efforts.

Slammed by some critics as being too slow to act in past disasters, Yudhoyono spent the first night after the quake sleeping in a tent along with survivors and moved his office to Yogyakarta to keep an eye on relief efforts, AP reported.

Meanwhile, activity at the nearby Mount Merapi volcano has tripled since Saturday's quake, experts told AP, and a large eruption is still possible.

Emergency aid only began arriving in two hard-hit districts of central Java on Monday, two days after the large quake flattened communities in this heavily populated Indonesian region.

The U.N. aid flight carried in water, hygiene kits and tents, according to The Associated Press, as rescuers sifted through the debris of homes searching for survivors.

Hospitals have been overwhelmed by the injured --- 2,192 of the 4,000 hurt are seriously wounded --- and medical workers fear tens of thousands of injured may not be receiving adequate treatment.

"Patients are still in the streets," said Malcolm Johnston, a representative of the International Federation of the Red Cross in Bantul. "Anywhere you can hang a drip, they're hanging a drip."

Many people have been reluctant to enter hospitals because they fear structural damage from aftershocks. Since the quake struck before dawn on Saturday, there have been 450 aftershocks.

"We need more paramedics and field hospitals to take care of those who are injured," Andy Mallarangeng, spokesman for Yudhoyono, told CNN on Sunday. (Watch traumatized survivors comprehend what's happening -- 2:12)

Hundreds of thousands went without shelter for a second night Sunday, living in makeshift tent cities or camping outside hospitals as they wait for help. (Watch the survivors camp in the debris, waiting for help -- 1:48)

"There are many, many, many people in misery right now," said Brook Weisman-Ross, a spokesman for the international children's charity, Plan International.

Most of the dead are being found in Bantul, a district near the Java coast just south of the historic tourist destination of Yogyakarta, about 250 miles (400 kilometers) southeast of the capital, Jakarta. (See where the quake hit)

Military troops have been deployed from Jakarta to help dig people out of the rubble and to evacuate victims.

The Indonesian government has allocated 75 billion rupiah ($8 million) for its initial emergency response, and on Sunday, Australia offered A$3 million ($2.27 million) for emergency food, shelter and medical supplies.

About 100 U.S. troops are bound for Yogyakarta to deliver supplies and equipment and help treat the thousands of injured people. The U.S. Marines, Air Force and Navy are involved in the effort.

The U.N. World Food Program announced Sunday three trucks carrying enough high-energy biscuits to feed 20,000 people for a week had arrived in the districts of Bantul and Klaten. (Watch tearful survivor tour destruction -- 2:36)

"The challenge is to make sure there is no mismatch between what is needed and what is being offered," said Dr. Marty Natalegawa, the Indonesian ambassador to the United Kingdom.

Earlier, WFP spokesman Trevor Rowe told CNN they were planning to bring in 80 tonnes of food, several teams of doctors and 2,300 kilograms (5,000 pounds) of medicine.

Countries across the globe pledged monetary aid adding up to millions of dollars. (Where to donate)

The 6.3-magnitude quake struck just before dawn Saturday about 15 miles (25 kilometers) south-southwest of Yogyakarta, near the volcano Mount Merapi.

Ring of fire
Indonesia sits on the Asia Pacific's so-called "ring of fire," marked by heavy volcanic and tectonic activity. Scientists are worried about the impact of the quake on Mount Merapi, which experts and villagers have watched closely in the past few weeks.

The nearby volcano has been rumbling for weeks, spewing out lava and hot gases.

On Monday the mountain spit out lava and hot clouds, sending debris four kilometers (2.5 miles) down its sides.

Since Saturday's quake, the volcano has spewed hot clouds an average of 150 times a day, compared to 50 times before, Subandriyo, chief of the Merapi volcanology and monitoring office who goes by one name, told AP.

Many aid workers anticipating a major eruption were stationed in the region, and they shifted their attention to helping earthquake survivors. Relief teams who remained in the area following the massive 2004 tsunami helped as well.

On Sunday, two strong earthquakes were reported in the Pacific, a 6.2-magnitude quake in Papua New Guinea and a 6.7-magnitude quake in Tonga.

The earthquake is the worst disaster in Indonesia since the December 26, 2004, magnitude-9 earthquake that triggered a tsunami, killing at least 131,029 people in Indonesia alone.

Another earthquake on March 28, 2005 killed about 900 people off the western coast of Sumatra.

CNN's Dan Rivers, Kathy Quiano and Al Goodman contributed to this report