(CNN) -- For Stephen Clapper, there was no choice after molten rock and sulfur dioxide gas spewed from the ground near his home on Hawaii's Big Island.
"We had to evacuate. My mother was out of portable oxygen, so that's a first concern. She's 88 years old," he told CNN affiliate KHON.
Clapper became one of hundreds of residents to flee the threats from the volcanic eruption. He said he told his mom on Friday morning to pack a bag, just in case.
But with lava setting trees ablaze and threatening homes, and with gas coming out of cracks in the ground, Clapper went back to the home, got his mother and the dogs, swept up some of his clothes in one arm, and took off for a shelter.
Cracks in Kilauea volcano's rift zone -- an area of fissures miles away from the summit -- erupted Thursday and early Friday, spurting lava in Leilani Estates, a community of about 1,700 people near the island's eastern edge.
Video posted on social media showed magma spewing several feet into the air from a new crack in a Leilani Estates street. Aerial videos showed lava searing a long orange and smoky line through a wooded area.
Jeremiah Osuna, who used a drone to record one of the videos Thursday, said the area "sounded like if you were to put a bunch of rocks into a dryer and turn it on as high as you could," according to KHON.
"You could just smell sulfur and burning trees and underbrush and stuff," Osuna said, according to the TV station. "I couldn't believe it. I was kind of shaken a little bit and realizing how real everything is, and how dangerous living on the East Rift can be."
Authorities ordered residents of Leilani Estates and Lanipuna Gardens to evacuate to two community centers, which are serving as shelters.
Eruptions from three small fissures in the Leilani Estates area -- mostly "vigorous lava spattering" -- continued into Friday, the US Geological Survey's Hawaiian Volcano Observatory said.
As of Friday morning, lava hadn't traveled more than "a few tens of yards" from the cracks.
"Additional outbreaks are likely," an update reads.
No injuries have been reported from the volcanic eruption, lava flow or fires, Hawaii County Mayor Harry Kim told the media.
There have also been hundreds of earthquakes this week, including a magnitude 5.4 temblor on Friday.
Leilani Estates resident Meija Stenback told CNN affiliate KITV that she left the area with her family. The eruption came after hundreds of earthquakes shook the eastern side of the Big Island over four days, and residents had been warned an eruption was possible.
"We knew it was coming, and even now it's ... really surreal at this point," Stenback told KITV.
A thick plume of smoke and ash also rose Thursday from the Puu Oo volcanic vent, roughly halfway between Kilauea's caldera and Leilani Estates.
Concerns about sulfur dioxide
Destructive molten flows weren't the only concern. Volcanic eruptions can release potentially dangerous sulfur dioxide -- and fire department personnel have detected high levels of the gas in the evacuation area, the civil defense agency said.
Exposure to high levels of sulfur dioxide could be life-threatening, according to the federal Agency for Toxic Substances and Disease Registry.
Breathing large amounts of sulfur dioxide could result in burning of the nose and throat and breathing difficulties, the agency says.
Senior citizens, the young and people with respiratory issues have extra incentive to leave the evacuation zone, because they are especially vulnerable to the gas, the state's Emergency Management Agency said.
Leilani Estates-area resident Stephen Clapper said he heeded the evacuation order in large part because his 88-year-old mother was out of her portable oxygen supply, KHON reported.
"I ran in, grabbed the dogs, put them in a crate, put them in the car, went in my room, just grabbed an armload of clothes," he said, according to KHON.
Gov. David Ige said he's activated the Hawaii National Guard to help with evacuations and security.
"I urge residents in Leilani Estates and the surrounding areas to follow instructions. ... Please be alert and prepare now to keep your family safe," he tweeted.
The Guard will do security patrols and help evacuate residents, Hawaii Adjutant General Arthur "Joe" Logan said.
Kilauea is one of the world's most active volcanoes. It's in Hawaii Volcanoes National Park, which has since closed off nearly 15,700 acres due to "the possibility of a new eruption and unstable geologic activity." But most of the park remains open, it said in a statement.
Since Monday, hundreds of earthquakes -- most of them around 2.0 magnitude -- have been recorded in the area. The series of quakes came after a collapse of a crater floor of Puu Oo.
The tremors have jarred residents, who've been reporting nearly constant ground vibrations. They have also reported cracks in roads.
"It has now become unnerving," resident Carol Shepard told KHON.
She said the flurry of earthquakes seemed to happen every minute.
"It'd be like the house would shake. It'd be like somebody that weighs 300 pounds came in my living room, and jumped up and down," she said.