Authorities said that six people were arrested in connection with the deadly explosion caused by illegal fireworks on New Year’s Day in a Honolulu neighborhood. They also confiscated 500 pounds of unopened fireworks at the scene.

Deena Thomas, Lt. of Honolulu Police Homicide, stated that two couples were arrested on Wednesday while one couple was arrested last Friday. She said that police expect to arrest many more people.

She said that the police were working with prosecutors on filing charges, but this was taking time because of the large number of arrests, the volume of evidence examined, and the testing of fireworks.

“We are identifying and recovering more evidence,” Thomas announced at a press conference that additional arrests would be made as a result.

Three women, a man, and a three-year-old child were killed in the explosion. About 20 other people were injured. A lit bundle of aerials in the style of mortars fell over and exploded into unlit fireworks causing a series of rapid-fire blasts.

Allegations of reckless endangerment in the first degree, endangerment of a minor’s welfare in the first degree, and multiple fireworks offenses led to all six suspects being arrested. The first two suspects were released pending an investigation.

Thoemmes stated that manslaughter is the most serious possible charge and the investigation was underway. She said that detectives would investigate how the fireworks were obtained and ask the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives to assist with this part of the case.

Thoemmes stated that the 500 pounds found at the scene were in the vehicle and carport of people who attended the gathering.

In recent years, Hawaii has seen an increase in the use of illegal fireworks. Many of these aerials are used in professional shows. Fireworks are set off all year round, but more so during the holidays.

Hawaii authorities say that existing laws are difficult for them to enforce in part because evidence is frequently incinerated by fireworks. Residents are often reluctant to testify in court against their neighbors.

Gov. Josh Green proposed overhauling the laws governing fireworks, including creating $300 fines for violators. He also requested that lawmakers allow for Class A felony offenses and possible decades of prison time for those who use fireworks to seriously injure or even kill others.

The Department of Law Enforcement of the state has requested that lawmakers appropriate $ 5.2 million to hire eight new employees and expand a laboratory to combat the rampant smuggling of explosives.

Police said the first two suspects arrested, a man and a woman both 33 years-old, ignited illegal fireworks at the New Year’s Eve gathering and allowed their children — ages 15, 10 and 1 — to also light illegal fireworks. The 1-year-old was injured, treated at a hospital and released, police said.

Thoemmes stated that the two couples arrested on Wednesday lived in the same house as the explosion.

A 35-year-old man and a woman, 38 years old, allegedly attended with their four children. All four children suffered injuries, were taken to hospital for treatment, and then released.

The other couple consisted of a woman, 29, and a man, 32. The police said that they were with their two children who were not hurt.

Thoemmes stated that some of the people interviewed by detectives initially made false statements.