"We're going to enforce crime and we're going to do it aggressively - and we're not going to apologize for it," said Charles Lawson, Chief of SEPTA Transit Police.
The most recent shooting happened Wednesday afternoon. Eight Northeast High School students between 15 and 17 years old were shot at a SEPTA bus stop in Philadelphia's Burholme neighborhood.
The gunfire rang out around 3 p.m. at Rising Sun and Cottman avenues. During a news conference after the shooting, Mayor Cherelle Parker said enough is enough.
"This is what's extremely important to me as mayor of the city -- that the people of the city know that we will not be held hostage, that we will use every legal tool in the toolbox to ensure the public health and safety of the people of our city," said Parker.
The shooting happened only hours after SEPTA police held a press conference to discuss safety.
WATCH: Police address increasing violence on SEPTA
SEPTA police address increasing violence on the mass transit system after 3 deadly shootings within
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"While it's tempting to draw the conclusion that crime is out of control on the system, it's really not true," Lawson said. "In fact, we are experiencing significant decline in virtually every serious crime category across the board. But it's this one that has us the most concerned. It's this category - gun violence."
On Tuesday evening, a 37-year-old was killed while riding a SEPTA bus in South Philadelphia.
The victim was on board a Route 79 bus near Broad and Snyder streets around 6:30 p.m. when he was shot twice.
Lawson said witnesses told police the victim and another rider got into a verbal confrontation, which quickly escalated into a physical fight.
"At some point, they both stood and that confrontation became physical and there are some punches thrown. At one point, the offender exits the bus and produces what we now know is a 9mm handgun and fires two shots back into the bus, right at the decedent," Lawson said.
The victim was taken to a nearby hospital where he was later pronounced dead, according to police.
Man shot, killed while on SEPTA bus in South Philadelphia: Police
Police say the shooter then got off the bus and headed into the Snyder Station along the Broad Street Line.
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The suspect was wearing a black jacket with a red lining in the hood, gray sweatpants and boots. He was also wearing a mask, police said.
Lawson said transit police will soon release some video of the incident.
There is no word yet on the victim's identity and police said they have not recovered a weapon.
Police say there is a $20,000 reward for information leading to an arrest and conviction in this case.
On Monday, a 17-year-old was killed and four others were hurt after gunfire broke out at bus stop in the city's Ogontz neighborhood Monday.
Teen killed in SEPTA bus stop shooting identified as Imhotep Institute Charter High School student
And on Sunday, 27-year-old Sawee Kofa was shot and killed after an argument on a SETPA bus in the city's Oxford Circle neighborhood.
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Argument on SEPTA bus leads to deadly Philadelphia shooting in Oxford Circle, police say
The recent shootings are putting safety on the transit system in the spotlight again.
"We're going to use every legal means at our disposal to target illegal gun possession on SEPTA," Lawson said. "We're going to be aggressive about that."
"As a father, I have a little girl -- she's 13 -- and I have my concerns with gun violence. She catches the bus by herself at home," said Marcus Tuggles. "We need to do something with gun violence. Bullets flying all the time."
To date, Lawson noted that over half the fleet has the ability to live-look in on the camera system remotely without requiring someone to be on the bus.
"We're going to leverage that technology in our fight against gun violence," Lawson said.
Lawson was asked about the enforcement SEPTA's face mask ban that was passed last year.
"There is no question that there is a level of fear among bus operators. We are exploring ways to make it easier for all of our employees report those things to us discretely, in a way that doesn't put them in jeopardy," Lawson said. "We encourage our customers to do the same."
He said customers can use the SEPTA app to discretely report anything that doesn't look safe to law enforcement.
"We want customers -- citizens of Philadelphia to reach out to law enforcement when they see something unsafe," Lawson said.
He also said they are "aggressively" adding more officers to buses and throughout the transit system, as well as more virtual patrol specialists. He noted that SEPTA has seen "tremendous successes" in its ability to decline crime on the transit system within the last six months since adding more of these resources.
Lawson said transit and city police will meet with city officials Wednesday afternoon about how to deal with increasing violence on the mass transit system, with recent shootings at the forefront of the discussion.
SEPTA officials also said they are focusing on the mental health of their employees amid fear following the recent events, including on-site counseling three days a week.
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