HARARE (Reuters) - Eleven people were killed and dozens injured in a stampede at a stadium in Zimbabwe, as thousands of people at a church service tried to leave through the same exit, police said on Friday.

Around 30,000 people packed into a stadium in Kwekwe, 213 km west of Harare, on Thursday evening to listen to Walter Magaya, a pastor who draws huge crowds, Senior Assistant Commissioner Shadreck Mubaiwa told Reuters.

When the service ended the congregation rushed towards a single exit, in a stampede that killed four people on the spot. Another seven were pronounced dead at a nearby hospital. "Police tried to rescue people but they were overwhelmed by the crowds. It is unfortunate that people wanted to rush out, which made it difficult to contain the situation," Mubaiwa said.

Mubaiwa said police were still investigating the cause of the stampede. Some people who said they had been at the service took to social media to accuse police and local government officials of opening only one exit.

Magaya was quoted by the online version of the state-owned Herald newspaper as saying that although the incident occurred after he left, he would take responsibility. "This was our event and as a church we have to take the blame for the tragedy," he was quoted as saying. "It is still too early to say what caused the stampede but the fact that the stampede took place at the venue means that part of our system failed to function."

Zimbabwe, hit by economic turmoil in recent years, has seen a rise in the number of "prosperity gospel" pastors, who preach that faith in Jesus Christ can lift people out of poverty.

In a country where 80 percent of the working population are unemployed, thousands flock to Pentecostal churches to contribute a chunk of what little they have in return for the promise of miracles to enrich them.

In September a building collapsed at a church compound in Nigeria run by popular preacher T.B. Joshua, killing 116 people, 81 of whom were South Africans.