About 380 migrants on Thursday managed to climb over a high border fence that separate a Spanish city in North Africa from Morocco, authorities said.
The Spanish government's delegation in Melilla said 1,200 migrants attempted to scale the 6-meter (20-foot) barrier that perimeters the city.
On Wednesday, a record 2,500 people tried to enter the city, resulting in 491 crossings, according to local authorities.
Spanish security forces activated an “anti-intrusion” mechanism early Thursday to confront what the government's delegation described as “extreme violence” by trespassers who “threw stones, used hooks and sticks” at border agents.
Four Civil Guard officers were treated for injuries at a local hospital, Sabrina Moh, the central government's delegate in the city, said at a news conference.
People fleeing poverty or violence sometimes use group incursion attempts to reach Melilla and the other Spanish territory on the North Africa coast, Ceuta, as a springboard to continental Europe.
Moh said the ones who succeeded this week were transferred to the local migrant centre, and authorities were evaluating their circumstances.
Melilla's border security with Morocco will be reinforced with 84 National Police and Civil Guard officers, Moh said.
Various nonprofits working with migrants in Melilla, including Solidary Wheels, said in a statement that activists saw how Spanish authorities sent back to Morocco three migrants who were found sitting at the top of the fence on Wednesday.
Mass border pushbacks are illegal under international refugee treaties because they deny people the opportunity to apply for asylum, although European courts have justified them in some instances.