pumping = ? pumping knives = throwing knives?

Context:
Celebratory gunfire and cries of "Allahu Akbar" or "God is Great" rang out across Tripoli as the reports spread. Cars honked their horns and people hugged each other. In Sirte, the ecstatic former rebels celebrated the city's fall after weeks of bloody siege by firing endless rounds into the sky, pumping their guns, knives and even a meat cleaver in the air and singing the national anthem.....