Pakistan’s former Prime Minister Imran Khan is in a stable condition after being shot and wounded during a protest march, a senior leader from his party said Friday.

Khan’s protest march and rallies were peaceful until Thursday afternoon’s attack, raising concerns about growing political instability in Pakistan, a country with a history of political violence and assassinations.

One of Khan’s supporters was killed and 13 others, including two lawmakers, were wounded in the attack.

“There is no doubt about it,” said Fawad Chaudhry, a senior leader from Khan’s Tehreek-e-Insaf party. “We are convinced that it was a well-planned assassination attempt on Pakistan’s most popular leader Imran Khan, who is now in stable condition at the Shaukat Khanum hospital in Lahore after undergoing surgery there.”

He said the party leadership was meeting in Lahore later Friday. “We will announce today exactly when our march will resume from Wazirabad,” Chaudhry told The Associated Press. He provided no further details, but Khan’s party in a brief statement urged supporters to hold nationwide rallies to condemn the shooting.

Asad Umar, a senior figure from Khan’s party, blamed the shooting on Prime Minister Shahbaz Sharif, the country’s interior minister, and an army general without offering any evidence.