Local hospitals indicate 18 people have self-reported to ER's complaining of minor injuries associated with the explosion on Gessner such as breathing problems and cuts. Health Department tests show there is no indication of any air quality concerns. — Houston Fire Dept (@HoustonFire) January 24, 2020

EMBED >More News Videos SkyeEye mapping technology shows just how close some of the damaged homes were to the explosion, some being only 300 feet away.

EMBED >More News Videos Police have shut down a number of streets in the 'hot zone' right around the explosion site in northwest Houston.

EMBED >More News Videos Here's what we know about the dangers of the smoke from the plant explosion in NW Houston.

SBISD facilities are fine as of this time, and we plan for a regular school day at all SBISD schools. We anticipate transportation delays. — Spring Branch ISD (@SBISD) January 24, 2020

HOUSTON, Texas (KTRK) -- At least two people are dead after a massive explosion rocked a northwest Houston neighborhood Friday morning, breaking windows, collapsing ceilings and even knocking houses off their foundations up to two miles away.Officials have identified Gerardo Castorena Sr. and Frank Flores as two victims who were killed in fatal explosions.The explosion happened around 4:25 a.m. in the 4500 block of Gessner Road. The origin of the explosion was at Watson Grinding and Manufacturing , a machining and manufacturing company, according to its website Houston police say the two victims are likely employees at Watson Grinding.Chief Art Acevedo informed the public that the son of Castorena was in the U.S. Marines and sent a plea to community members advising them to reach out to the Marines in order for him to come home immediately. Over twenty-four hours later, the Marines agreed to let the solider travel home to be with his family, according to the military group 'Boots for Troops'.A man who spoke to ABC13 said his 6-year-old niece was taken to Memorial Hermann Greater Heights Hospital to be checked out. He said her family's house is close to the business that exploded and that his brother told him something fell on the little girl's head. The family is waiting to get more information about her condition.Fire officials say at least 18 people have visited local emergency rooms, complaining of minor injuries and breathing issues. Witnesses told ABC13 they saw two injured people walk out of the debris field moments after the blast.The largest debris field and damage is in the area between Gessner and Steffani Lane in the Westbranch neighborhood. As of Friday afternoon, police closed off two nearby neighborhoods - Westbranch and Carverdale - that were impacted by the blast.Houston Fire Chief Sam Pena said 180 to 190 homes have some damage.Officials aren't 100 percent sure of the identity of the victims, but they say there is a high probability they are workers because they're the only two people missing and their vehicles were at the location.Acevedo said families of the two victims have been contacted and he asked that people pray for the families.Chief Acevedo said residents would be the only people allowed to go back to those neighborhoods. Earlier, he said patrols will be watching the neighborhoods where people left their homes. He warned looters will be charged."You will not be given a slap on the wrist. I want you to think back to Hurricane Harvey when we caught someone looting and they were sentenced to 20 years in prison," Acevedo said.Entire structures were destroyed in the blast. Homes were blown off their foundations in the adjoining neighborhood, authorities said. Broken windows, doors, and garage doors were also reported across a wide area around the blast site.As a result of the blast, at least 48 people were directed to a temporary shelter at the Church of Jesus Christ of Latter-day Saints on Shadowdale Drive, according to the Houston Fire Department.An overnight shelter was later set up at the Fairbanks United Methodist Church at 14210 Aston St.The ATF was responding to the site, although the Houston Fire Department will remain the lead agency, according to ATF spokesperson Nicole Strong.The agency later added that its five National Response Teams were sent to Houston, consisting of 30 members who include arson investigators, bomb technicians, scientists, and engineers.Dogs have been brought in to assist with searching the area.Firefighters were walking door to door in a neighborhood next to the blast site. Crews were being advised to move away from the area as the response continued.There was no evidence of terrorism or that the cause of the explosion was intentional, according to Acevedo.The owner of the facility told Eyewitness News the explosion originated from a propylene tank. Propylene is an extremely flammable gas that is used to make a variety of products.Two Cy-Fair ISD schools, Bane Elementary School and Dean Middle School, were closed Friday after the explosion. Spring Branch ISD remained open, but will keep students inside due to air quality concerns, according to a statement from school district officials."In an abundance of precaution, students will remain indoors at nearby schools due to air quality concerns. We will continue to monitor the situation and provide updates on the website and social media as they become available," Cy-Fair ISD officials told ABC13.As schools prepare to let out for the day, Cy-Fair ISD officials said that all neighborhoods that were accessible by buses in the morning should be accessible by buses again in the afternoon. They asked parents to be patient as there could be transportation delays. If students are not able to be safely transported home, they will be returned to the campus. Parents will be notified to pick up their children from the campus.