(From 5-2-18)

Hawaii's Big Island was rocked early Thursday morning by an explosive eruption at the Kilauea Volcano, which sent ash and debris shooting some 30,000 feet into the air and prompted emergency officials to urge everyone near the peak to shelter in place.

Meanwhile, miles east of the summit, another fissure opened in the ground in a residential neighborhood where nearly two dozen large cracks have spewed lava over the last two weeks.

"Hawaiian Volcano Observatory reports that an Explosive Eruption at Kilauea's Summit has occurred," said Hawaii County Civil Defense in a Facebook post. "The resulting ash plume will cover the surrounding area. The wind will carry the plume toward the southeast."

The eruption, which occurred just after 4 a.m. local time, likely lasted only a few minutes, USGS geophysicist Mike Poland told the Associated Press. In the hours that followed, 18,000 ash masks were distributed to local residents, and more were to be handed out Friday, according to Honolulu Star-Advertiser reporter Gordon Pang.

"There was a little bit of shaking there right after, but I never heard like an explosion or anything," resident Joe Laceby, who lives a few miles from the summit, told the AP.

(MORE: Dramatic Before-and-After Images of Hawaii Lava Destruction)

No injuries were reported in the eruption. Officials were hopeful that the eruption wouldn't be deadly as long as nobody was in the areas of Hawaii Volcanoes National Park that have been closed since last Friday, when the risk of a large eruption began to increase.

Elevated sulfur dioxide levels in the area forced officials to close several schools on Thursday, the Star-Advertiser also said.

The ash, which had been coming from the crater, Halemaumau, for days, prompted a "red alert" for all aircraft in the area, the Hawaiian Volcano Observatory announced Tuesday. Impacts to airplanes by airborne ash can be extremely dangerous, as the fine-grained particles can disrupt plane engines, according to the USGS.

A flight restriction was expanded to a 5-mile radius around the volcano and 10,000 feet above the volcano, FAA spokesman Ian Gregor said in an AP report. Airlines are flying as scheduled.

(PHOTOS: Kilauea Volcano Erupts)

To the east of the main crater, authorities were also monitoring a series of fissures that have claimed several homes and are threatening to move into additional residential areas. This would make new evacuations necessary, officials also said.

Those evacuations would impact residents in the Puna area, where at least 21 fissures have sent lava shooting into the air at various times over the past two weeks, Hawaii Army National Guard commander Brig. Gen. Kenneth Hara told the AP. The evacuations would become necessary if lava covered important highways and threatened to keep those residents from getting out of the area, he also said.

"All Leilani residents be aware of new activity, downed power lines, higher level of fumes and take necessary precautions," said a Hawaii County Civil Defense alert issued Thursday afternoon as the 21st fissure formed.

In the Leilani Estates and Lanipuna Gardens neighborhoods, where most of the 1,800 evacuees reside, lava has destroyed 37 structures, 28 of which were homes, according to officials.

"It sounds like a war zone," resident Lisa Rios told Hawaii News Now. "The sounds of the eruption were very eerie."

The 17th fissure stretched hundreds of yards in length near Halekamahina Loop Road, the Honolulu Star-Advertiser said. With cracks forming in Highway 132, which has been used for evacuating hundreds of residents, officials worry that an additional fissure could shut down the roadway.

"In the military, we like to have two ways to exit out of a dangerous situation," Maj. Jeff Hickman, public affairs officer with the Hawaii National Guard, told Hawaii News Now. "If that road does get cut off, we do start to plan for a mass evacuation. It is a dangerous situation. We're trying to plan for the worst."

(MORE: Kalapana, Hawaii Burning: The History of Kilauea's Catastrophic Lava Flow)

Residents near the fissures have been warned that dangerously high levels of sulfur dioxide are emerging from several vents, and vulnerable residents could be sickened.

Air quality was "condition red" for areas of southeastern Lanipuna Gardens and nearby farm lots, according to an alert sent to those residents Monday afternoon. This means the air quality is a serious health risk, and residents who haven't evacuated could experience choking, inability to breathe and other symptoms, a Hawaii County alert said.

Officials are allowing evacuees to return to their homes to check on their belongings and said residents would be able to go back to their homes every day from 7 a.m. to 6 p.m. until further notice.

Updated estimates say the eruptions could cost the island $5 million in cancellations by tourists from May through July, Big Island tourism board executive director Ross Birch told the AP.