(CNN) -- Pro football player Donte Stallworth was in stable condition Sunday after a hot air balloon he was riding in crashed into power lines, his lawyer said.
Doctors at Miami's Jackson Memorial Hospital were treating Stallworth and a female companion for severe burns, attorney Christopher Lyons said.
Police said the hot air balloon they were riding in plunged to the ground after hitting power lines in Miami on Saturday. The balloon's pilot was not injured, CNN affiliate WSVN reported.
"I appreciate all the prayers and well wishes more than you know," Stallworth said in a Twitter post late Saturday. "I feel lucky to be alive."
The National Transportation Safety Board is investigating with the help of Miami-Dade police, Detective Roy Rutland said.
The California native began his NFL career in 2002 with the New Orleans Saints and most recently played for the New England Patriots. He is a free agent.
Drew Rosenhaus, Stallworth's sports agent, said Saturday that his client is "in good spirits."
"He was injured, but will be fine," said Rosenhaus, adding later that he hopes Stallworth is back playing "in a matter of weeks."
"He will be able to resume his NFL career," Rosenhaus said.
Beyond his on-field exploits -- from his time at the University of Tennessee to his years playing with the Saints, Patriots, Philadelphia Eagles, Cleveland Browns, Baltimore Ravens and Washington Redskins -- Stallworth is known for hitting and killing construction worker Mario Reyes, who was crossing a street in Miami in 2009.
Under a plea agreement, Stallworth was sentenced to 30 days in jail for DUI manslaughter. He also reached an "amicable" settlement with the Reyes family, Lyons said. The NFL also suspended him for one season.
CNN's Rick Martin and Greg Botelho contributed to this report.