(CNN) -- A second death in Dallas may be linked to a rave last weekend that ended in chaos, police said.

Howe Police Chief John Cherry said 22-year-old Kyle Haigis attended the Electric Daisy Carnival hours before running onto a highway and being killed by a tractor-trailer.

A friend who was with Haigis told police they bought and ingested street drugs billed as ecstasy at the concert, Cherry said. The pill was described as a yellow pill with a caricature of a runner on it.

According to police, the men stayed until the rave was shut down at 2:30 a.m., but began arguing on the way home.

"Kyle just started going nuts, fighting with his friend," Cherry said. "He then grabbed the gear stick and slammed the truck into park, blowing out the transmission."

The friend told police he and Haigis continued to argue until Haigis said, "Well, this should end it." He then opened the door and ran onto North Central Expressway where he was hit by a semi.

Officials with the Dallas Police Narcotics Division said they are investigating what took place at the Electric Daisy Festival, but do not have the authority to investigate Haigis' death directly.

A 19-year-old man also died in Dallas Sunday after leaving the concert but police said they are still investigating the cause. Rescuers responded to a series of 911 calls from the carnival for emergencies related to drugs, alcohol and excessive heat, fire department spokesman Jason Evans said.

Some 20 to 25 people were taken to hospitals for treatment, with one reported to be in critical condition.

The emergency calls began as early as 9 p.m. Saturday with at least 10 rescue units sent to the scene at the Centennial Building in Fair Park, Evans said.

"The chaos finally came to a rapid stop when someone pulled a fire alarm around 1:30 a.m. and sent those remaining scattering," he said.

Two citations were issued by fire inspectors, one for overcrowding and another for failure to obey the order of the fire marshal. His request for a half-hour halt in the music to help manage the crowd was refused, Evans said.

According to the Electric Daisy Carnival website, the sold-out event began at 4 p.m. and was due to end at 2 a.m. It was open only to those over 18 and drugs and other illegal substances were banned.

A spokesman for the carnival issued a press release Monday urging participants to take care of themselves and friends while attending the concert.

"We are deeply saddened by the tragedy that occurred and we ask you all to keep the man who passed away and his family in your thoughts and prayers," the statement said.

We work "hard alongside local law enforcement to create a safe and secure environment for festival-goers, and that requires your help and participation."

Frank Librio, a spokesman for the city's government, said in an e-mailed statement that the "event was conducted with all of the proper procedures, approvals and safety measures," including driver's license screenings and bag searches.

"No outside beverages were permitted, other than a sealed water bottle," Librio wrote, noting that the same event last year occurred without incident. "Festival rules were posted at all entry points."

The spokesman added that Dallas' fire and rescue department had "three medical assistance stations" in Fair Park for the event.

"There were no issues with air conditioning, which was fully operational," said Librio, despite reports about high heat.

The death of a 15-year-old girl from a suspected drug overdose at an Electric Daisy Carnival event in Los Angeles last year led to calls for a ban on raves at the venue involved.

The Electronic Daisy Carnival is in its 15th year. This year's carnival started in Orlando, Florida, in May and will end in Puerto Rico in late August. The carnival will be in Las Vegas this weekend, according to the website. Tickets for the Vegas concert start at $200 for a single-day pass and go up to $500 for a 3-day VIP pass.

Fair Park, a former World's Fair site and National Historic Landmark, hosts the Texas State Fair each fall.